I was confused by the title. Apparently epics are a way to organize issues by themes across projects. GitHub doesn't have this concept, in case anyone else was wondering.
You can also add them to GitHub via ZenHub and other such tools.
?
I'm unsure as to whether that's a good thing or not.
1) https://github.blog/2021-06-23-introducing-new-github-issues...
Scroll down to "break issues into actionable tasks", and they have an example that's even labeled as an "Epic". They are definitely headed in the same direction as Gitlab.