Virus alert popup?

Your phone does not have a virus. Period. End of discussion. There are no viruses that can infect an iPhone. If you have a storage problem you need to address that. But also keep in mind that while it is called an iPhone, it is actually an extremely powerful pocket sized computer that can also make phone calls. Like any computer it needs to be “rebooted” periodically, by turning it off, waiting a minute or two, and turning it back on. It’s a good idea to do that once a week or so.

It’s a scam. Ignore it. If you have trouble getting rid of it see—>Dealing with Safari popups that won&#… - Apple Community