I want to update my iPhone to ios 16

Is your phone qualified to update to iOS 16? You will need an iPhone 8 or higher model to update to iOS 16.

What is the Model Name of your phone? Settings > General > About > Model Name

You need to have an iPhone 8 or higher model to update to iOS 16.

iPhone 5, iPhone 6 and iPhone 7 cannot update to iOS 16.