The IE series has some quality RPGs, though I'll warn you that they're very different from Underrail. PS:T, BG, IWD are all widely lauded as great RPGs and staples of the genre. There is ofc FO 1 & 2 which was a big source of inspiration for this game, but IMO I don't think very highly of these games and think Underrail improved upon them in almost every conceivable way, but I'd be remiss if I didn't mention them.
Disco Elysium and AoD are newer age RPGs that are also very good, though I'll warn you that DE has no traditional combat and is very much a story focused game.
Banner Saga was a series of cute, turn-based tactical "RPGs" which I enjoyed and could merit taking a look at due to the artstyle, music, and world.
Finally, if you like Star Wars I enjoyed the KotOR series which, despite being third person RPGs, are still really enjoyable to me for some reason and really satisfy my Sci-Fi itch.
Just some suggestions to get you started.
