Neoteny is the scientific term for physical, especially facial features that make one look younger. These include but are not limited to:
larger eyes
smaller noses
rounder faces
less pronounced chins
I took about 800 or so faces of Asian and European women aged 18 - 35 and calculated the "neoteny" of their faces and labeled the 1/3 or so highest scoring images with the trigger word "neoteny".
Try using a weight of about 0.75 to start. If you want closeups of faces, try a score of 1.0. If you're only getting closeups, try reducing the weight on the LoRA.