After create your avatar image, add this:
8k zoom into her face, with hyper-realistic skin texture, realistic youthful skin texture with very fine, minimal pores lightly visible on cheeks and nose, soft, smooth overall appearance, mild under-eye softness appropriate for a young face, tiny freckles or skin specks scattered lightly and sparingly, healthy, breathable skin, natural softness without blur, no airbrushed effect, no plastic or porcelain finish.
Full tutorial: