How to downgrade to 16.0.1

How to uninstall iOS or iPadOS beta software - Apple Support

Follow the steps in the article that sent you here.

16.1 isn’t the publicly released iPhone update. You have the beta version. 16.0.1 is the update that is publicly available. You need to follow all of the steps in the article. Otherwise you can try contacting Apple directly maybe but the reps for the beta release are what’s in the article.

Are you using a Beta since 16.0.1 is the latest official release that I’m aware of? Are you able to delete the Beta version?

If you received an update to 16.1 your in the beta program. Follow the instructions in that article to remove the beta profile from you iPhone then restore it as a new device (not from your backup).