This article explains how to add a photo widget on an iPhone.

There are several ways to customize your iPhone’s home screen, and adding a photo widget is one of the options. When you add the photo widget to your home screen, a selection of your photos will appear in a set position. You can move the location of the widget if you are not happy with where the system has placed it.

Here's how to add the photo widget to iPhone:

Press and hold an empty area on the screen until the icons start to wiggle.