I installed Opera Stable rpm file and Opera web browser

I installed with software install. When i check installed software it it shows not installed. This prevent me from adding html 5 support for this browser. My Vivaldi browser and stable works fine.
How do I get dnf to find opera?

See Manual setup Opera RPM repository setup instructions

You need to add a ‘opera.repo’ file to /etc/yum.repos.d/ containing the following

name=Opera packages
baseurl=Index of /rpm

One issue I’ve found is that Opera, having ‘opera-stable’, ‘opera-beta’ and ‘opera-development’ rpms available seem to somehow end up with identical .build-ids in different versions such that it can be difficult to install, for example, both opera-stable and opera-beta at the same time. If you only use one version, it works fine.