how can I update my iphone. my phone said “unable to verify update because you are no longer connected to the internet” while I have an internet 🥲🙄

You need to fix the No Service issue first before you can update over WiFi. It requires both a WiFi connection to download and a cellular connection to verify.

If it's telling you that you need to update to use cellular, it means you need to update your carrier settings, not your iOS. Look here -

Update your carrier settings on your iPhone or iPad

Manually update your carrier settings on your iPhone or iPad - Apple Support

Also look at this article -

If you see No Service or Searching on your iPhone or iPad - Apple Support

Once you have that sorted out, you should be able to update using WiFi. If you can't update that way, you will need to use a computer. If you don't have one, ask a relative or friend who has one if you can use theirs. You can also go to an Apple store and ask to use one of theirs.