How do I upgrade latest iOS version on my iPhone 7 Plus?

To update to the most recent, compatible version, please see: Update your iPhone, iPad, or iPod touch - Apple Support

And: If your iPhone, iPad, or iPod touch won't update - Apple Support If the above Apple articles do not help, please post back with relevant information. 

Hello,

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

iPhone 7 will only update to iOS 15.8.3

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

The iPhone 7 Plus originally ran iOS 10. You can update it to the latest release of iOS 15, but that is the end of the line for that phone.

You cannot update an iPhone 7 Plus to iOS 16, 17, or 18.