My iPhone 7 is not updated

Have you previously used a beta version on the device?

If so, remove the beta profile, restart the phone and check again for the update.

If this is not the issue, please post back with relevant details as to what happens when you attempt to update.

Hello,

There are different ways to ensure the highest iOS that your device will support is installed on your device.

This support article has instructions about updating an iPhone or iPad wirelessly --> Update your iPhone or iPad - Apple Support

You can also use Mac and PC computers to update system software:

Update iOS on iPhone - Apple Support

or:

Update iPadOS - Apple Support

If your Apple mobile device won't update, read this support article --> If your iPhone or iPad won't update - Apple Support

Another, less common reason for not being able to update is if you were using a beta version of software. Refer to How to uninstall iOS or iPadOS beta software - Apple Support

Possibly: How to uninstall iOS or iPadOS beta software - Apple Support

Failing that, have you worked your way through the Apple links provided by Limnos above?

What is the existing version of iOS?

What happens when you attempt to update?

Did you try the various ways I posted?

You checked all the reasons why an update might not happen?