Frotz (free, no ads/iap) will let you install and play text adventures like “Flexible Survival” (NSFW open world survival) or “The Wizard Sniffer” (SFW comedy adventure). I haven’t played “Metamorphoses” or “Counterfeit Monkey” yet, but I hear that they both have TF as central elements as well.
“Pathos: Nethack Codex” (free, no ads/iap) classic roguelike) will let you play as a changeling or werewolf and has polymorphing spells, and “Cataclysm: Dark Days Ahead” ($1, no ads/iap, very hardcore survival roguelike) apparently has TF mechanics similar to “Caves of Qud” on PC, but it’s a bit too hard to get into for me. It’s definitely harder to learn than “Dwarf Fortress.” (An older version is also on the App Store. It’s free, but AFAIK does not support tiles)
The Shantae games are worth mentioning as well. (SFW-ish, $5, no ads/iap for Risky’s Revenge, Apple Arcade sub for 7 Sirens) It’s all poof TF, but the games themselves are pretty good metroidvania style platformers.
Outside the App Store, the best places to look are Itch.io and TFGames.site.
Itch requires an account (and a toggle in your user settings) before you’ll see NSFW games in searches.
On both sites, you’ll be looking for browser-playable games.
I might come back to this comment to add some Itch/TFGames recommendations, but that’s all I’ve got in me to write for now.