OpenAI highly recommended, as with all RPG bots or any bot involving established/real world characters, that doesn't use purely OC characters. GPT's database is almost infinite when it comes to fiction and non-fiction, especially 4 or 4o.

Do what you want. Real world? Go for it. Fictional variation of the real world? All good. Want to base it in Skyrim, or Mass Effect? Bingo. Want to roleplay as Ciri's husband after the events of The Witcher 3? All yours. Want to be the Verdugo from Resident Evil 4 and wreak havoc in a post-apocalypse setting like Fallout or The Walking Dead? Click me. Do whateverrrrrrr you want with me! A straight up sexual scenario fantasy where you explore suppressed desires? Right here.

(Seriously, at least use GPT 3.5 minimum if you want the bot to know anything about the universe you want to play in.)