UDIMs are handled as Streaming Virtual Textures (SVT) in unreal engine. Sorry, I've just realised I've assumed that's what you're using, disregard me if it's not. I'm not sure what the state of UDIM support is in any other engines. to have fun
that is really not hard to research tho. for one there is unreal engine for fortnite which iassume gives you access to some of it? buit besides that, sketchfab has a ton of fortnite characters ripped, so you can just check it out there.
What engine are you using ? UE ? Despite the engine, I would recommend to let the engine work for you. see, if you put all texture in a single UV, you will need a huge texture to maintain texel density for each character. Unreal have very clever ways to optimized VRAM allocation. What you are planning to do, goes in the…