Your iPhone can develop a faulty button, and you might end up not being able to adjust your volume. Well, this method of adjusting your volume without using the dedicated buttons is not really that new, but a lot of people are still unaware of how to use it.

This feature will work with the Assistive Touch feature on your iPhone, so if you have not enabled Assistive, go to your Settings > Accessibility to enable it.

Follow the easy steps below to start adjusting your volume without using the button on your iPhone.

First, you must have enabled the Assistive Touch feature in your Accessibility settings...

Source:
https://www.hownaijablog.com/2022/06/01/how-to-adjust-volume-up-or-down-without-button-on-an-iphone/