That's tough. Akbal, the jaguar in the deep woods, does a bit of that, with a focus on anal.
Not slave, but Sophie likes to dom and I think gets a bit degrading if the player had a small penis.
Losing to Izma, the futa shark girl at the lake, has her taking an alpha role and making you her beta.
In the /
hgg/ mod, losing to the Ivory Succubus has vibes like that. (your balls will hurt if you have those)
The game has quite a bit of domination, but the degrading and enslaving variety doesn't easily come to mind. You could try enslaving Ceraph. She has a lot of roleplay sex options which probably has some degrading slave-play for you to be sub in.
You could also play the SUPER old prison mod from long before the game was finished. It's rough around the edges, but you get locked in a cell and degraded, forced to accept becoming a slave to avoid deeper humiliation or being sexually used by the imp guards.