For foreign films, Swept Away… by an Unusual Destiny in the Blue Sea of August (aka just Swept Away, by Lina Wertmuller, is all about class conflict. (Not to be confused with the remake starring Madonna, which I haven’t seen but understand is awful.)
Not a class conflict at all, but an ethnic one. The white Jets were just as poor as the Puerto Rican Sharks, and lived in the same crappy neighborhood.
Also an ethnic conflict, not really a class one. The Nativists led by Bill the Butcher were at most only a tiny step above the immigrant Irish they were battling. They both lived in the poor Five Points neighborhood.
Another WWI movie is Howard Hughes’ Hell’s Angels, here the class bickering is between a pair of British flyboys and a German officer. Also between one of the flyboys and flighty Jean Harlow in her first major role.
Lifetime movie, I bet. Lifetime probably has a lot of movies along those lines, going back to the grandmommy of them all: “Imitation of Life” which has racism as well as class conflict going on. A lot of those old potboilers had class conflict: “Mildred Pierce” would be another one. But most of them are not fun. Tears were what they were after, not laughter.
Kubrik’s Barry Lyndon, setting is not modern; but it has a certain timelessness IMHO - I think it highlights the complexity of social mobility in a way that few other things I have seen does. Chariots of Fire to some extent. I think Wall Street is a really good one for something more modern.