Board Thread:Support Requests - Getting Started/@comment-46004342-20201006112803/@comment-46664455-20201006134243

You can only change the name of the user groups, this by editing MediaWiki:user-identity-box-group-. Add the name of an existing user group after the "-", example: sysop, blocked, founder, etc. (Note: Wikitext does not work, you can only change the name)

If you want to add custom user groups, you would need to contact Fandom's staff.