How to update latest software on iPhone

There are no new updates for the iPhone 7. iOS 15.8.3 is the end of the road.

Unless you have not updated in a very long time, you already have iOS 15.8.3.

Check as follows: Settings > General > Software Update

Your tag line says that you have an iPhone 7 running iOS 14. You can update it to the latest version of iOS 15.

About iOS 15 Updates - Apple Support

Update your iPhone or iPad - Apple Support

Updating iOS: common issues and solutions - Apple Community

You cannot update it to iOS 16, 17, or 18 – if that is what you are asking about.

Go to Settings > General > Software Update and it will show if there is an update available. The iPhone 7 is capable of iOS 15.8.3.