Eh, it’s heavily dramatized and was recorded in English but HBO’s Chernobyl miniseries might be worth checking out if you’re interested in things like one-party rule and conspiracies in authoritarian regimes.
TIL China is a one-party system with English subs
A good documentary, on the USSR though not modern Russia, is The Human Face of Russia. You can find it on YouTube. It’s Australian as well so it’s interesting seeing a look into the Soviet Union from the point of view of a country that is aligned with the US but without so much Red Scare propaganda.
A day in the life of Ivan Denisovich
Its a movie based on a book by Alexander Solzhenitsyn, about a man in a russian gulag. You can find it on Youtube.
Not a series but Death of Stalin is a super funny movie that is actually closer to reality than one might think.