I’m getting virus notifications on my iPhone and IPAD how do I prevent this

They are all scams, so you can safely ignore them. See→Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

If you see them in your calendar here is what to do→Delete spam calendars and events on iPhone - Apple Support.

If you get them in email or messages just delete them.

And if you see them in your web browser go to Settings/Safari and tap Clear History and Website Data.