I have the same issue. After making a 911 call my Note 9 was stuck in Emergency Calls Only.
Easy Fix.
1. Swipe down from the top to get Notifications Screen.
2. Scroll through Notifications until you get to the one related to Emergency Calls Mode and tap on it.
3. On this screen, drag the red X on the bottom right towards the left (center of the screen) to Exit Emergency Calls.
You should now be out of emergency mode.
This worked for me.