On Rocky Linux 8 it requires both EPEL and powertools.

On Rocky Linux 9 is requires both EPEL and crb (powertools).

If you don’t have those on, you will see:

dnf install nagios-plugins-all
 
Error:
 Problem: package nagios-plugins-all-2.4.9-1.el8.x86_64 from epel requires nagios-plugins-disk_smb, but none of the providers can be installed                                                       
  - package nagios-plugins-disk_smb-2.4.9-1.el8.x86_64 from epel requires perl(utf8::all), but none of the providers can be installed                                                                
  - conflicting requests
  - nothing provides perl(PerlIO::utf8_strict) needed by perl-utf8-all-0.024-7.el8.noarch from epel                                                                                                  
(try to add '--skip-broken' to skip uninstallable packages or '--nobest' to use not only best candidate packages)