Red Hat Repository Info

Is there an easy way to get information about Red Hat repositories?

If I want to know what content is in the Optional, Common or Supplementary repositories is there a source for that information on the Red Hat site? Can I browse the repository packages on a site some place?

I found this link: https://access.redhat.com/articles/1150793

Which sort of explains what the Optional and the Supplementary repositories contain but doesn't go into any great detail. I have tried to find information about rhel-7-workstation-extras-rpms, what it contains and why I would need to use it but failed.

Besides trial and error or poking around on an actual system I am not sure how to find decent information about the repositories. For every other distro I have used it is pretty painless to go and look at the repo data.

Hopefully I am just missing something and there is an easy way to get detailed information about the different Red Hats repositories, what packages they contain and why I might need to use them.

I am guess it is probably to much to ask for detailed information like this for each repository:
https://access.redhat.com/documentation/en-US/Red_Hat_Software_Collections/2/html/2.3_Release_Notes/chap-RHSCL.html#sect-RHSCL-About