How can I display the user group of everyone on their own page on my wiki? Maybe in the title header? I was looking for this all over the internet but could not find anything. I want to do something similar to what can be seen on admin or staff Wikia user pages next to their names. I know that on Wikia people can change what is displayed there for each user group on the "MediaWiki:User-identity-box-group-<group-name>" pages. For admins for example it is the MediaWiki:User-identity-box-group-sysop page(This seems to be kinda similar but still different than the "MediaWiki:Group-<group-name>", "MediaWiki:Group-<group-name>-member", "MediaWiki:Grouppage-<group-name> pages".).
Topic on Project:Support desk
It's one of wikia's many custom extensions.
There are similar extensions like Extension:SocialProfile.
You can also use a script like UserWikiInfo.js that will look like this. CSS Styles are in MediaWiki:Monobook.css (find "UserWikiInfo" rules) and MediaWiki:UserWikiInfoContribs if you want to display contribution breakdown on "content" namespaces vs global and you have Extension:Editcount. If you know JS and CSS you can basically tune it to your needs