The character has several skins, as well as several heads.

I also added a rifle and a pistol that have bones to move parts.

The character now has 2 rigs, one rig for version 4, the second rig for version 5 of the engine.

You don't need to retarget. You just need to do a reassignment. I showed it in the video.

Thank you very much

Video:Presentation

Video:Test Epic Skeleton UE4

Video:Test Epic Skeleton UE5

Video:Tutorial