Why can’t I update my phone with WiFi connection
What ways I can updates my phone with data connection
iPhone 7 Plus, iOS 14
If your tag line is correct and you have an iPhone 7, you cannot update using cellular data. The only iPhones which can update using cellular data are iPhone 12 or newer with 5G service. If you don't have Wifi, you can go somewhere where you can use Wifi, or you can update using your computer with iTunes.
See how to update using a computer here --> Update your iPhone, iPad, or iPod touch with iTunes - Apple Support
