The artist is drawing Hololive vtubers (mostly Hololive Japan) in chibi-ish style.
USE WEIGHT HIGHER THAN 1.0
For the exact style from pictures above, add "amazing face, perfect face, Detailed" to the prompt, although, I'd say that use of facefix/adetailer is REQUIRED.
This LORA is available at Pixai.art and Tensor.art