This issue is how Metahuman Creator makes female head jaw-line looking way too masculine. This is particularly obvious in and accentuated in Asian faces.
Internally that base mesh is closer to a medium-build male skull: the mandible is wide, the angle of the jaw is low and the masseter muscle area is bulky.
When you switch the preset to “female” the system only scales the whole head 92-94 % and softens a few landmark distances; it does NOT remodel the underlying bone.
The result is a jaw that keeps the male flare and squareness—what artists call the “man-jaw”
Asian fashion-model references you see on Instagram usually combine:
a narrow bigonial width (≤ 80 % of cranial width)
a 120–125 ° mandibular angle (very acute)
minimal masseter volume
Those three metrics sit outside the allowable range in MetaHuman’s Identity Solver.
If you feed a custom sculpt that already has that sharp jaw, the solver “corrects” it back to the statistical average that its PCA space contains, so the jaw pops back out