What kinds of RPG are you looking for. Quite a few to recommend on Gamepass. Do you want a more shooter/first-person style RPG or rather something tactical. If it's the former you can't go wrong with Fallout 3/New Vegas/4/76. The Outer Worlds is similar in style, but in space. Starfield is the most recent, but I never really got into it. Again, it's in space and also similar to the ones I've mentioned. Of course Skyrim is also worth it, if you haven't already played it. Would also recomment the Mass Effect Legendary Edition as that trilogy is just one of the greatest ever, but you need to have EA Play for that. Not sure if that is part of every Gamepass or whether you need ultimate for that (if you don't have it on Gamepass, it's currently available in the Steam-sale for 9 Euros or your local equivalent. I would definitely recommend it for that price, if you like that kind of game.
Tactical RPGs I would recommend on Gamepass are Wasteland 3, Pillars of Eternity 2 and Wartales.
If you like RPGs with more freedom and base-building/crafting/survival/farming/open-world elements I would recommend Medieval Dynasty, Mount and Blade II Bannerlords, Grounded and Stardew Valley.