Great film. Had to wikipedia a few times.

If you’re interested in exploring this more, there are a few more films you can watch.

RKO 281 - HBO film about the making of Citizen Kane. Mank is played by Malkovich With superb cast.
https://www.imdb.com/title/tt0120801/

The Cat’s Meow - portrays the infamous pleasure cruise aboard Hearst’s yacht with Marion, Charlie Chaplin and Thomas Ince, the latter of whom is shot dead during the cruise. Decent cast. Bogdonovich film.
https://www.imdb.com/title/tt0266391/

The Hearst and Davies Affair - self explanatory. I haven’t watched it in a while. Made for tv.
https://www.imdb.com/title/tt0089260/
https://www.youtube.com/watch?v=vGKpLgZFuvc

Chaplin, if you haven’t already seen it, apparently also has Marion Davies. (I really don’t remember her in it; need to rewatch).