iOS 18 has several new features and shortcuts that have largely gone unnoticed. One such feature is the ability to switch cellular data plans on your iPhone.

You can now open the Control Panel and long press on the 'mobile data' option to switch between the two networks.

Additionally, you can also set the Action button to switch between mobile data. Use the link here for the shortcut that switches between data lines. The shortcut checks which line is active and automatically switches to the other.

Considering how useful the Action button can be, it may not be ideal to use it to switch between cellular data lines. However, it can be useful to do so if you need to change active data multiple times a day.