How can I update my iPhone software?

Whether, and how far, you can update iOS will depend on which iPhone you have.

If your iPhone is not running the latest version of iOS (18.*), but is telling you that iOS is up to date, that means it is running the latest version compatible with it, and cannot be updated to a higher major iOS version. For instance, it is not possible to update an iPhone 6s, 6s Plus, 7, 7 Plus, or SE (1st generation) to iOS 16 or higher. For all of those iPhones, iOS 15 is the end of the line.

If there are further updates available for your iPhone, the steps to update it are as outlined here:

Update your iPhone or iPad - Apple Support

Updating iOS: common issues and solutions - Apple Community

What model of iPhone do you have?

Have you checked to see if that model is still qualified for updates?

It is not about what you want, but how far your phone can get updates.

You have the oldest Apple phones? The chances are zero.

Relatively new devices? The chances are 50-50%.

A new device? The chances are 100%.

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