How to find out if my iPhone has a virus

Do not install any type of AV software. There are no iOS viruses to find. On top of that, iOS is a highly protected OS. All apps must run in a sandbox. They cannot talk to, or share anything with other apps or the OS. Making any such AV software 100% useless.

Yes, they exist on the App Store, but none of them are actually AV software. All they can do are simple things like clearing cache files and cookies. Something you can easily do your yourself without the need of such trash software.

There are NO known viruses for iPhone. If you saw a popup suggesting you do have one, it's a scam.

usually your iPhone is safe from viruses and malware but if you’ve been doing sketchy things like jailbreaking or

side-loading, that removes your safety and reassurance and I would recommend using a 3rd party security check like avast. Take in mind i could be wrong since im not very experienced with viruses

You're welcome. Yes, iPhone is immune to virus, unless you have jailbroken your phone, which is very difficult to do.