Ineed to change my iPhone ios to ios 16

Your tag line says that you have an iPhone 6 Plus, and your message says that you are running iOS 12.5.7.

Your phone cannot run iOS 13 or higher. iOS 12.5.7 is as good as it gets for that phone, right now. If you want to run a newer version of iOS, you will need to get a more recent iPhone.

gift63 Said:

"Ineed to change my iPhone ios to ios 16"

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Updating an iPhone 6 Plus to iOS 16:

You Can't. This is not an option. Your iPhone model(6s Plus) is incompatible with iOS 16 - Apple. It can only go to iOS 12.5.7. And, for the note, even if you could update, only the latest-compatible version will install.

So, what to Try:

B. Update Using a Computer:

Have a Computer Handy? If so, try using a computer to update. Go here: Update your iPhone Using a Computer - User Tip. If any updates are availabe, they will install, sure enough.

You can't, sorry.

See why in this compatibiity chart: