Completely customise your Metahuman heads with more accuracy in this 3-part video. Requires Maya2020, Zbrush(optional), Unreal Engine 4.27 or similar and Quixel Bridge with Epic Games account.
Part 1 is available for free, please support me by purchasing via Artstation
Important things to note: Changing the shape of the mesh will not change the position of the joints that deform that face, so the more you change it from the original metahuman mesh, the more the distortions may fall out of position when animated, it has to be quite extreme though, and for the most part, as long as you keep the eye positions and scales you will be fine. The trick is to export the eyes also into Zbrush,. to be sure you do not deviate from their original position, also try to keep the mouth at the same location too.
This method can be used for most cases, but if you want perfect results, the DNA file would need to be regenerated using other methods not yet available.