Open with Blender 4.0 or above.

The character is rigged with rigify:

https://docs.blender.org/manual/en/latest/addons/rigging/rigify/index.html

Collection are well organized in 3 main layers:

-Studio

-Character

-Armature

Eyes are made with tiny eye addon:

https://tinynocky.gumroad.com/l/tinyeye

Watch the video for know more about customisation:

https://youtu.be/PalITj_NuIA?feature=shared

Enjoy!