How to check if I have a virus on my iphone

You don't have a virus on your phone. Scammers sent you a message containing a pack of lies, to try to trick you into contacting them for "help", or into purchasing an app to fix a non-existent "problem."

I've seen several variations on the "Your data will be corrupted" or "Your hardware will be damaged" scam theme, including messages that have an animated countdown timer, ticking down the seconds to the point at which your phone or computer will supposedly be irreparably damaged.

There's another example of this sort of scam here:

U.S. Federal Trade Commission – How To Spot, Avoid, and Report Tech Support Scams

The sample scam message includes the warning "DO NOT TRY TO MANUALLY REMOVE THE VIRUS. HARD-DISK FAILURE MAY OCCUR." This is supposed to panic you so that you react without thinking, and deliver yourself right into the "tender loving hands" of the criminals who sent the message.

Something similar is what they tried on you.

it is a scam - ignore it.

To avoid more nagging, Go to Settings, apps, Safari (or on ios17, Settings, Safari) and Clear History and Website Data