UE4 Mannequin has a precise collision on their skeletal mesh, how did they achieve this?

I am making a game that requires 1 giant enemy to have precise collision on their body, however “complex as simple” doesn’t work because the giant enemy is not a static mesh. and I noticed that the UE4 Mannequin has a very precise collision box on the skeletal mesh, and I cannot find anywhere that explains how this is done. for a reference to the collision, I have recorded this short video with collisions view turned on. View here