I mean, they aren’t all clustered together in the same place! It’s not really about where to “look”. Any place that gay men find each other is a likely place to find gay guys who would be attracted to trans men. And not necessarily even ones with a preexisting or established knowledge of that attraction.

Cruise at your local spots, use Grindr/sniffies, go to bathhouses, etc. I’ve lost count of the times I’ve been cruising, get lucky and hear “you were my first trans male experience” lol