Recommended generation parameters:

CFG Scale: 6, Sampler: Euler A, Schedule type: SGM Uniform/Align Your Steps

Positive prompt: masterpiece, best quality, absurdres

Recommended negative prompt: lowres, bad quality, worst quality, bad ???????, jpeg artifacts, signature, watermark, sketch

I also recommend using this upscaler: https://openmodeldb.info/models/2x-AnimeSharpV4