You might wanna try dating apps, its often easier than most would like to meet swingers and couples looking for their third, their unicorn. But negotiating a threesome is more difficult than most of them are ready for.
Oh you sweet bean. I really want to comment on this and not be dismissive. But I am quite old and very sexualy experimental. I'm polyam with two partners and I've been a bull for couples before. But thank you for trying to direct people that maybe less knowledgeable then myself. Keep being kind!