The iPhone 7plus updated

Your iPhone 7Plus can be updated to iOS 15.7.3, but the built in hardware does not support any further iOS 16 upgrade.

iOS 15 and iPadOS 15 are compatible with these devices - Apple Support

iOS 16 and iPadOS 16 are compatible with these devices - Apple Support

To use Wi-Fi to update your iPhone, follow the steps mentioned in this article:

Update your iPhone or iPad - Apple Support

Or, if you are using a computer or Mac:

Update your iPhone, iPad, or iPod touch with iTunes - Apple Support

Update your iPhone, iPad, or iPod touch with the Finder - Apple Support