The tag for porn games is erotic or adult, but I don't know of a more precise tag, or even if one exists...
The reference "similar games" when it is there can give some pretty good games if you look a little (top right of the game pages): https://itch.io/games-like/1649873/confined-and-horny
Otherwise a very good game that I am currently playing is "The Headmaster": https://altosandherdone.itch.io/the-headmaster
...otherwise I had two or three games that I had tried on my pp, you never know, maybe I'll try to add things :)
(Google translate, sorry)