What do I do to protect my phone from viruses

You don't have any viruses on your phone, it is a scam message designed to get you to purchase unnecessary software.

Read more about it here -

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

josselyn197 Said:

"What do I do to protect my phone from viruses: When I’m on a website my phone randomly shows this thingy where it shows that I have 2 strong viruses"

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Protecting iPhone from Viruses:

You don't. You will not get a virus on your iPhone. This "thingy" is a scam message. So, ignore it. Keep antivirus software off of your Apple devices.