How do you stop iPhone from going into Do Not Disturb?

With Focus in iOS 15 and iPadOS 15 or later, you can use Do Not Disturb to silence calls, alerts and notifications that you receive while your device is locked. You can also schedule Do Not Disturb and allow calls from certain people.

When you have Do Not Disturb turned on, a crescent moon icon 

1. Go to Settings > Focus.
2. Tap Do Not Disturb.
   
   
3. Under Turn on Automatically, set Do Not Disturb to turn on automatically at a certain time, location or while using a certain app.

To turn on Do Not Disturb from Control Centre:

If you don't want to be disturbed at a certain time, you can set a schedule and change other Do Not Disturb features to help you concentrate.

1. Go to Settings > Focus.
2. Tap Do Not Disturb.
3. You can select allowed or silenced notifications from people and apps, connect your Lock Screen or Home Screen, have this Focus turn on automatically, and add Focus filters.