I'm dating a handful of people, and I want two of them to form a triad with me

I have four partners all of which are separate from each other meaning no group dates or anything but they know about each other. one is genderfluid like me, one is a cis man, one is a trans man, and one is a trans woman. they're all fine with me being polyam but they're all monogamous except the cis man. I find myself wanting to be with the cis man and the trans man in a "triad" I think it's called, I want the three of us to have a beautiful relationship. I don't know how to bring it up.

It’s pretty impossible to just “want” other people into a relationship. People don’t develop emotional, sexual, or romantic attraction to each other on command. It doesn’t work like that!

Your best bet is to start out by just introducing them to each other in a low-stakes, low-pressure way. Having your partners be comfortable and friendly with each other is a much easier ask than wanting them to date each other. Of course, there’s no guarantee that they will like each other. Sometimes people just don’t click, and that’s okay - you may really want them to, but they can’t force it and they’re not obligated to. Sometimes, civility and politeness without genuine friendship is all we can ask of metamours.

But there are things you can do to help make it more likely that they will get along. I discuss this here (and link other answers in the same vein).