can I revert to an earlier OS version?

Yes you can but it's not recommended.

To do so you'll need to wipe your drive and reinstall the earlier version.

https://www.makeuseof.com/tag/downgrade-macos-version/

Be absolutely certain you have good, viable, very recent backups and that they are accessible for use by either Setup Assistant or migration Assistant.

The computer can only downgrade to the version of macOS it Originally came Installed with as New.

Be aware, that the earliest version you can install is the one that the Mac shipped with.