I'm new to Daz3D, just wondering if you are able to create your own face texture for Daz3D models (like you can in iClone)
Yes, but not in DS or poser. You have to create them in another app and import them. 2D programs like Photoshop or GIMP. Some of the #D programs let you do it also.
if you mean the face fitting function
Faceshop by Abalone in store or Singular inversions facegen plugin for Daz studio Genesis are the two main possibilities.
Faceroom in Poser for Poser only figures another but not terribly good and limited to their native content
faceshop standalone will even work on iClone content 3dxchange head mesh exports