How to update my iphone
How to update my iphone and my sim network doesn’t work
iPhone 7, iOS 14
How to update my iphone and my sim network doesn’t work
iPhone 7, iOS 14
If you need to run iOS 16, you cannot; the last version of iOS supported by the iPhone 7 is iOS 15, the last version of which as I write this is iOS 15.7.3.
About iOS 15 Updates - Apple Support
If you are asking how to update to a later version of iOS 15, follow the normal update instructions here:
Update your iPhone or iPad - Apple Support
Finally, if you are having SIM issues, contact your cellular carrier for assistance.
If you need to run iOS 16, you cannot; the last version of iOS supported by the iPhone 7 is iOS 15, the last version of which as I write this is iOS 15.7.3.
About iOS 15 Updates - Apple Support
If you are asking how to update to a later version of iOS 15, follow the normal update instructions here:
Update your iPhone or iPad - Apple Support
Finally, if you are having SIM issues, contact your cellular carrier for assistance.
There are only 2 ways to update an iOS/iPadOS. Know how to...

Before any iOS / iPadOS update, please do the following
Go to Settings > General, and tap Profiles & Device Management. Tap the iOS Beta Software Profile. Tap Remove Profile, then restart your device --> How to uninstall iOS beta software - Apple Support

VPN or proxy connections might prevent your device from contacting the update servers.

If you still can't install the latest version of iOS, try downloading the update again:
If you don’t see the update in the list of apps or if the issue happens again, you need to update your device with iTunes.

Try updating iOS after each step.

You can update your iPhone, even without SIM, to iOS 15.7.3 by going to Settings -> General -> Software Update and wait for iOS 15.7.3 update to appear and download and install the update. However, your iPhone cannot be upgraded to iOS 16.
Please check this article it has all the different methods you need to update your iPhone.
Update iOS on iPhone - Apple Support (AE)
Please make sure to backup your phone prior to updating Back up iPhone - Apple Support (AE)
How to update my iphone