I received a suspicious email saying I have 5 Viruses on my iPhone

As mentioned above, that’s a scam

Mark that message as junk, and get on with the rest of your day.

Some of many common scams and schemes:

… Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

PS: If you’re using an iPhone 6s Plus per the footer, consider updating your iOS to the most current for that model; to iOS 15.

All such messages are scam presented by criminals. Do not interact with the message or the sender. Do not download anything based on such bogus messages.

Well, most scams mention something like 13 viruses, but this one and anything like this that you might see are scams trying to trick you into doing something that you would otherwise never do.

Don't be fooled.Delete the messages.