How to Adjust Alarm Volume on iPhone
On your iPhone, first, open the Settings app. In Settings, scroll a bit down and tap “Sounds.” If you don’t have the “Sounds” option, tap “Sounds & Haptics” instead.
On the “Sounds” page, find the “Ringer and Alerts” slider.
To decrease your alarm’s volume, drag this slider to the left. To increase the volume, drag the slider to the right.
As an alternative, you can control your alarm’s volume using your physical volume keys. To be able to do this, on the “Sounds” screen, toggle on the “Change with Buttons” option.
And you can now press your volume keys to adjust the alarm volume.
Want to play a bit more with your alarm settings? Try changing the tone that plays as your alarm sound.