Grindr is full of kinky people. It's also full of ad spam and bots. Scruff is a little more dignified but it's mainly for bears, and the more attractive of them sometimes put things like "no fem" on their profiles. The only one I wouldn't recommend is Recon, which is kink-focused, and only because I've never even come close to getting a date through that, though I am in the US.
Apps I haven't tried: I hear Barq is good for furries. Feeld is a kink-focused app but I think it's mostly straight people.
Honestly I have trouble getting my two partners to like each other, or even tolerate me for more than a day at a time. If I "allowed" someone to have a 3-way I'd "allow" them to finish wherever and however they want.