How do we update without WiFi

You can update using the cellular connection if you have an iPhone 12 or an iPhone 13 with 5G service and iOS 15.x. You have an iPhone 11 and you can, therefore, only use a Wi-Fi connection or ➔ Update using a computer.

Axel F.

You'll need to use either WiFi (which is ubiquitous; stop by a library, coffee shop, McDonalds, etc.) or connect your device to a computer and update through iTunes (PC) or Finder (Mac). https://support.apple.com/en-us/HT204204