That's a modified version of the DAZ V4 high-rez materials.   The shader settings are pretty much set to default, the texture has been modified kind of a lot (lightened, a faint bit of freckles).  Probably the biggest change is actually the lighting, also your suggestion originally; 4096 shadowmap and shadow min bias of something like .2 or .25 ... setting it smaller tends to make the shadow go funny, with a visible bright offset from the part casting the shadow.

I tried a variety of values to subtract all the way up to 1.0, and I'm satisfied with .5 really - as you say the proper thing to do is use a displacement map on all the zones so this isn't an issue, or be prepared for a little bit of postwork.

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