Sherif Dawoud is a talented environment artist, but he is also a sculptor who creates fantastic realistic characters. You can see how his models start as clay-like blobs and slowly turn into detailed faces with impressive textures in the artist's latest time-lapses.
The ZBrush sculpts are gorgeous in their complexity: skin and lips show age-appropriate wrinkles, and the lighting highlights the signs of exhaustion.
There are plenty of anatomy studies on Dawoud's X/Twitter, not only of faces but also of bodies, so if you need a reference, go check them out.