my iPhone 12 is stuck on a call screen

I made a call to a number. While the phone was calling, I tried to stop the call as the person I was calling then called me on MS Teams. But my iPhone 12 got stuck on the "calling... Some One" screen.

The phone now won't allow me to make a call; the message says I can't place a call while I'm on another call.

I tried repeatedly to switch off the phone, it won't switch off.

I removed the sim card, no difference. What do I do?