The dnf repolist command will the repositories you have enabled. Refer to enable or disable a DNF repository.

dnf repolist

Something like this should be returned.

repo id                  repo name
fedora                   Fedora 34 - x86_64
fedora-cicso-openh264    Fedora 34 openh264 (From Cicso) - x86_64
fedora-modular           Fedora Modular 34 - x86_64
updates                  Fedora 34 - x86_64 - Updates
updates-modular          Fedora Modular 34 - x86_64 - Updates

The repos should be listed in .repo files in the /etc/yum.repos.d directory.

~]# ll /etc/yum.repos.d
-rw-r--r--. 1 root root 7378 Mar 12 04:19 fedora.repo