Why can't my iPhone 7 Plus upgrade to iOS 16?

Hello,

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

iPhones 6S through 7, and SE(gen. 1), will currently update to iOS 15.7.8

This support article has instructions about updating an iPhone or iPad wirelessly --> Update your iPhone or iPad - Apple Support Read the article for recommended criteria for being able to use wireless updating.

You can also use Mac and PC computers to update system software --> Update iOS on iPhone - Apple Support

If you want a video about doing this, follow this link —> https://www.youtube.com/watch/1FcE86kwODQ

When updating, your device will update to the highest version currently available that it will support, or it will just say it is up to date (and can't go any higher) and won't install anything. If you want to run a higher system version than your current device is capable of running, you need to buy a newer device.

Apple doesn't say why.

An iPhone 7 does not have the hardware needed to run anything higher than iOS 15.7.8

Because it lacks the hardware, RAM and CPU power to correctly run iOS 16 or later.

Due to hardware limiations, that iPhone is too old to run iOS 16