Your description of artists' life is pretty simplistic and one-sided. There were some people who did propaganda posters, but there were many things that existed outside the political domain, from book illustrations, to paintings with less ideological overtones, to working in theater. There was also Soviet cinema and animation, which would hardly be seen as only a propaganda vehicle, there was a lot of very nuanced works, which raised important questions. A lot of good stuff was shelved, or circulated underground of course.
The Russian Novel That Foresaw — but Underestimated — Totalitarianism
https://www.newyorker.com/books/second-read/the-russian-nove...
It is an interesting film in general, and in context of your comment from the politics of art perspective -- it starts with a Nazi lecture on the "degenerate art" of 20s-30s, to art class lectures in Communist times, and ends with the equally ideological forces dictating "what's art" in West Germany (where are hero finally achieves fame and fortune.) It's East German variety of old regime/new regime but likely will resonate at some level.