This probably isn't the repo you're looking for.
A long while ago, back when this blog was built with Jekyll, I had some Jekyll-specific posts. How to build tag pages, etc.
I haven't used Jekyll in a while, and so I can't say for sure whether those old approaches still work, or are still a good way to solve the issue of building a tag-specific page.
This repo has a bunch of stars and forks and followers from back in the day, but is now a (kind of messy) place where I'm (again) trying to keep a blog.
Good luck finding whatever it is you're looking for! I sincerely hope you find it!