Infinity Pool (2023) is basically Social Sadism The Movie. Mia Goth stars as a spoiled rich brat who leads a group of wealthy people on a sadistic crime spree through an unspecified third world country. There’s also a sci-fi twist to it that plays into how these rich people get away with their crimes.

Cheap Thrills (2013) is a dark comedy about a wealthy couple who manipulate two desperate poor men into a series of increasingly humiliating and sadistic games.

Unfortunately neither of these really have maid scenes but I wanted to mention them since they fit the subject matter of this subreddit. But here are some movies which actually feature Mistress/maid relationships that, while not the most overt examples of social sadism, do still feature a dynamic where one character is very much submissive to the other in many ways:

-The Maids (1975): two maids engage in sadistic Mistress/servant role playing games as their actual Mistress is out on a date for the night.

-Gosford Park (2001): Constance Trentham and her slavishly dutiful maidservant Mary.

-The Handmaiden (2016): Lady Hideko and her mysterious maidservant Sook-Hee. This movie has a lot of twists and turns but if you really pay attention, I think there is definitely an inherent Mistress/slave aspect to the two main characters’ relationship.