I received a text message I have a virus, what can I do

If the notification is appearing in your calendar, see:

If running iOS 13 or earlier versions, check: Settings - Passwords & Accounts - Accounts - Any rogue entries here? If so, delete the rogue account. 

If running iOS 14 or higher, check: Settings - Calendar - Accounts - Any rogue entries here? If so, delete the rogue account. 

The Apple support article is below. 

Remove calendar spam

Video support

Vanessapage wrote:

I got a message asking should they lock my phone due too much spam has been detected

Ignore it and delete it. That’s a “phishing” scam to steal your identity, your money, or both. See→Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support