iPhone 12 has a virus how can I find and delete it

iOS / iPadOS devices cannot be infected with Virus / Malware / Spyware unless you have intentionally downloaded spurious software or unauthorized apps directly from the internet and installed them on your device or/and have Jailbroken. 

Why do you think your phone has a virus?

If you saw a message that a virus was detected on your phone, it is a common scam that is trying to trick you into buying useless software.

Scam. Hopefully, you have NOT tapped on any links.

There is no virus on your phone unless you gave your phone to someone for an hour or two and also gave them your Apple ID and Password.