I'm fairly focused on China (studied China in university, speak Mandarin, live in China, read about 50 books on/about China during the past 10 years).

While there are plenty of books that can give you a general feel or a broad understanding of some trends in society (Age of Ambition: Chasing Fortune, Truth, and Faith in the New China, China in Ten Words, China's Millennials: The Want Generation), and there are a few books regarding specific parts of the government/policy (The Party: The Secret World of China's Communist Rulers, Out of Mao's Shadow: The Struggle for the Soul of a New China, Wealth and Power: China's Long March to the Twenty-first Century, When A Billion Chinese Jump: How China Will Save Mankind Or Destroy It
), I don't know of many books that are focusing specifically on authoritarianism. I suspect that there are quite a few journal articles from political science scholars who focus on Chinese government/governance.

One assumption I have here is that you only/primarily would read in English. If you can read in Chinese, then there is a far more vast swath of literature available from Hong Kong and from Taiwan about China.

Books I’ve read that relevant to things like the possibility of stable and/or global totalitarianism

• The Totalitarian Threat, by Caplan, 2008
  • This is actually one chapter from the book Global Catastrophic Risk, which was edited by Bostrom and Cirkovic
    • And I haven’t read most of the rest of the book
  • Clicking on the following link will download a doc version of this chapter: link
    • You can see the link here
  • This is the only chapter/paper-length treatment of this topic that I’m aware of
  • I’d recommend this chapter both in general and for the specific purpose of learning about this topic
• The Precipice, by Ord, 2020
  • Totalitarianism is only the focus for a brief section of Chapter 5
  • But the rest of the book is excellent anyway
  • I’ve roughly ranked this as 1st out of 44 EA-related books for how generally useful to me it seemed (not just for totalitarianism etc.)
  • I’d recommend this book in general, and would recommend the relevant section of Chapter 5 for the specific purpose of learning about things like totalitarianism 
  • See here for some thoughts on this and other nuclear-risk-related books.

Novels:

• 1984, by Orwell, 1949
  • Despite being a novel, I think this book is actually the most detailed exploration I've seen of how a stable, global totalitarian system could arise and sustain itself. 
    • I think this is a sign that there needs to be more actual research on that topic - a novel published more than 70 years ago shouldn't be one of the best sources on an important topic!
  • I’d recommend this book both for reading for enjoyment and for learning about things like totalitarianism
• Animal Farm, by Orwell, 1945 
  • I’ve roughly ranked this as 42nd out of 44 EA-related books for how generally useful to me it seemed
  • I wouldn’t recommend this book except for reading for enjoyment
• Brave New World, by Huxley, 1932
  • I’ve roughly ranked this as 43rd out of 44 EA-related books for how generally useful to me it seemed
  • I might recommend this as an interesting exploration of a possible type of future, but probably not
  • I probably wouldn’t recommend for reading for enjoyment (I found it dull at times)

Thanks! Also interested in this.

This syllabus on authoritarian politics might be useful. I found these parts especially interesting (some are papers rather than books, but hopefully close enough):

• "What Do We Know About Democratization After Twenty Years?" (Geddes, 1999)
  • Discusses the relative longevity of different kinds of authoritarian regimes
• "Civil Society and the Collapse of the Weimar Republic" (Berman, 1997)
  • On how the Nazi Party used civic associations to expand its power in the Weimar Republic
• Parts of Totalitarian and Authoritarian Regimes (Linz, 1975), especially from ch. 2:
  • Pp. 65-71 on definitions of totalitarianism
  • Pp. 129-136 on criticisms of the concept of totalitarianism
  • P. 137 has a list of earlier scholarly work on democratic backsliding (pretty old though)
• Development as Freedom (Sen, 1999), especially pp. 178-88
  • On the fact that “There has never been a famine in a functioning multiparty democracy”

Also:

• Economic Origins of Dictatorship and Democracy (Acemoglu and Robinson, 2005)
  • Historical case studies and model of transitions to (and from) authoritarianism
  • I really liked ch. 2 as an overview

Books I’ve read that are relevant to things like authoritarianism generally (not just one or two specific regimes), democratic backsliding, etc.

• The Dictator’s Handbook, by de Mesquita & Smith, 2012
  • This is somewhat less focused on dictatorship itself than one would think from the title, but is still relevant and quite interesting.
  • I’ve roughly ranked this as 25th out of 44 EA-related books for how generally useful to me it seemed (not just for understanding authoritarianism etc.).
  • I’d recommend the book both in general and for the specific purpose of learning about things like authoritarianism
• How to Be a Dictator: The Cult of Personality in the Twentieth Century, by Dikötter, 2019
  • The author engagingly presents a series of interesting and important historical case studies.
  • But I’m not sure how much knowing more about those case studies will actually help me learn other things or make good decisions. And, if I recall correctly, the author provides very little in the way of analysis or recommendations, except in a somewhat rushed and superficial seeming way at the very end of the book.
  • I’ve roughly ranked this as 38th out of 44 EA-related books for how generally useful to me it seemed.
  • I’m unsure whether to recommend this.
• The WEIRDest People in the World: How the West Became Psychologically Peculiar and Particularly Prosperous
  • This is loosely relevant, in the sense that it discusses a range of different types of societies and political systems, some implications these different systems have, historical trends towards more democracy, and potential drivers of those trends
  • I haven’t quite finished the book yet
  • I’d recommend the book in general, though probably not for the specific purpose of learning about things like authoritarianism
    • ETA: I've now finished the book, and stand by that assessment. See also my notes on the book.
• Books that may have had relevant parts (e.g., on pros and cons of democracy vs authoritarianism, or historical trends in these things), though I can’t remember for sure:
  • The Better Angels of Our Nature, by Pinker, 2011
    • See here for some thoughts on this and other nuclear-risk-related books.
  • Against the Grain, by Scott, 2017
    • See also this interesting Slate Star Codex review of the book
  • The Myth of the Rational Voter, by Caplan, 2007
  • Enlightenment Now, by Pinker, 2018
  • Radical Markets, by Posner & Weyl, 2018
  • (I’ve roughly ranked those books as 15th, 22nd, 28th, 33rd, and 37th out of 44 EA-related books for how generally useful to me they seemed)

Books I’ve read that are relevant to China

• Age of Ambition, by Osnos, 2014
  • This is the one book I’ve read that’s focused on China.
  • I’ve roughly ranked this as 26th out of 44 EA-related books for how generally useful to me it seemed (not just for understanding China, authoritarianism, etc.). 
  • I’d recommend the book both in general and for the specific purpose of learning about China
• Destined for War, by Allison, 2017. 
  • That’s focused on the likelihood of war between the US and China, how to prevent it, etc. So it’s relevant to China, but not focused on China’s political system, regime, etc.  
  • I’ve roughly ranked this as 24th out of 44 EA-related books for how generally useful to me it seemed. 
  • I’d recommend the book in general, though probably not for the specific purpose of learning about China’s political system
  • See here for some thoughts on this and other nuclear-risk-related books.

I also recently started the free online course Chinese Politics Part 1 – China and Political Science, which was recommended to me by another EA. I’m not far enough into it to be able to recommend it myself. (I’m intending to just watch the videos during some mealtimes and do the quizzes, skipping the assignments and certificate.)

As for books I haven’t read (at least not yet), Darius Meisner wrote elsewhere:

On the rise of China (relevant to Great Power Competition), I have found it interesting to read Superpower Interrupted: The Chinese History of the World by Michael Schuman. However, I am not too excited to recommend it, because the great majority of the book covers developments in ancient China for which the level of "insights per page" was fairly low for me.

Books[1] I’ve read that are relevant to things like the Soviet Union or Russia

• The Dead Hand, by Hoffman, 2009
  • This is primarily a history of the Cold War with an emphasis on nuclear and biological weapons, rather than a history or analysis of political systems or authoritarianism
    • But of course the topics are interrelated, so the book does have some relevance if one wishes to understand the political systems of the Soviet Union and Russia
  • I’ve roughly ranked this as 20th out of 44 EA-related books for how generally useful to me it seemed (not just for Russia, authoritarianism, etc.)
  • I’d recommend this book in general, but probably not for the specific purpose of learning about things like the political systems of Soviet Union and Russia
  • See here for some thoughts on this and other nuclear-risk-related books. 

[1] Well, just "book", really - hence the request for recommendations!

Also, here's a reading list on democratic backsliding, recently posted as a comment by Haydn Belfield.

Timothy Snyder is an academic looking at this question who has written several books on the topic, e.g. this and this. 

I think 'How Democracies Die' is a pretty acclaimed book that seems relevant.