Your emergency contacts have been notified

Your description is consistent with the Emergency SOS call. Have you accidentally made one of these calls?

The result of that call is described here - For a limited period of time, your device will send updates to your emergency contacts as your location changes. You’ll receive a notification when this happens.

Try to force restart your phone. The instructions are here which are: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the side button. When the Apple logo appears, release the button.

• Restart the device. That's it.
• Still not solved --> Force restart iPhone - Apple Support

• Follow the Apple article to resolve the issue --> If your iPhone, iPad, or iPod touch won't turn on or is frozen ...