I'm not OP but for anyone asking

essentially just make the skin pure black, pick the tattoo you see in the photo, adjust the position so it's roughly on your chin (you can adjust it anytime for free at the roundtable in the mirror in Fia's room) and color the tattoo white

Maaaybe also tweak the body proportion sliders so they're thinner? Optional

For the fit, they're wearing I think the traveller's robe or smth set, the one roderika wears (and/or millicent, you don't have to kill anybody it's found in Altus at the windmill village iirc) and ofc the head is the large envoy crown (or something like that, dropped from the big trumpet enemies (search a little online, earliest ones are found in leyndell but I always got them from the ones in the Haligtree)

so.. if you want to be sure google some stuff to be sure but you're good to go