If you are doing anime games, you can try VRoid Studio. It's very easy to customize a character, like a video game, but the graphics look a little dated.
I've been meaning to check it out for a long time — thanks for the reminder :)
In terms of character customization capabilities it reminds me of the generators from Illusion:
AI Shoujo Character Creation
Unfortunately, the resulting character is not very easy to transfer to a 3D modeling program.
I suppose a good idea would be to create a similar character generator in Godot with the ability to export to more popular formats for use in games. It could be based on MakeHuman.