Glad you asked! I should preface all this by saying you can't really like "learn" any real socialist theory from Civ 6 but what I mean is that Tokugawa is probably the best civ in the game for beelining for the Communist government type and a Scientific or Cultural victory.

Bakuhan inflicts penalties on international trade whilst making domestic trade routes (which usually yield Food and Production but not much else) generate Culture, Science, and Gold equal to how many Districts are at the source (in addition to Food and Production). It also makes all your cities within 6 tiles of the capital permanently loyal and therefore immune to being conquered period.

Meiji Restoration makes Japan's district adjacency bonuses way better as well which allows you to carefully build very tightly and efficiently where other civs would feel boxed in.

In Civ 6, Communism as a form of government focuses on production and defensive strength; adopting it automatically gives land units an extra +4 defensive strength, and makes your cities +15% more productive. Policy cards unlocked by the Class Struggle civic include Collectivization which makes domestic trade routes yield way more food, Defense of the Motherland which makes modern units cost 100% less production and reduces War Weariness, and Five Year Plan which makes Industrial Zone and Campus adjacency bonuses even MORE powerful.

So when you put it all together, Tokugawa is overwhelmingly the best pick for if you want to play a communist style game. He wants you to create a dense, tall civ that focuses on land management and production that can easily resist aggressive, imperialist civs. It's kind of funny how he has little to do with socialism historically but turned out to be such an outright communist civ lol. If you're going into a new game wanting to take full advantage of the Communist government type, he's probably who you want to choose.