Mostly you will create a Rig object in the engine and specify which chain of bones match across the two characters. At this time I don’t have any UE5 specific retargeting tutorials. For the time being you will need to rely on unreal documentation or other sources to do retargeting on the engine side.
On the Blender side things remain as they are shown in the videos wrt to the UE4 mannequin.
Uefy v2.5 is currently under development with support for the newer manny and quinn mannequins with higher bone count. Once that is released, I will begin work on new videos specific to unreal engine 5.