The best settings :

Euler a

Checkpoint : WAI-NSFW-illustrious-SDXL - V14

steps : 25

CFG : 5

Clip skip : 2

prompt : masterpiece, best quality, amazing quality, fine details, Nahida, female child, solo, breasts, flat breasts, long hair, white hair, green hair, gradient hair, gradient hair, side ponytail, bangs, hair between eyes, braid, pointy ears, green eyes, symbol-shaped pupils, cross-shaped pupils, hair ornament, leaf hair ornament,