iPhone 11 virus in Messenger.

Are you referring to the Apple Messages app or the Facebook (aka, Meta) Messenger one? If the latter, you will need to contact the developer for assistance with this matter.

Ref: How to contact an app developer - Apple Support

joakimsa wrote:

iPhone 11 virus in Messenger. What to do?

There are no known virus/malware/spware for a non jailbroken phone.

Explain what you mean in messenger.

Why do you think so?

There are no known viruses that can affect iPhones.

What exactly are you seeing in messages that makes you think there is a virus?