My phone has been updating for 4 plus hours. Does it usually take that long to update?

Not it doesn't take that long. Generally an update is completed within 30 - 40 minutes if all conditions are good. If you are using the update through Wi-Fi Network method then the Wi-Fi connection must be very good, Ensure that your iPhone is plugged in and charging while connected to the Wi-Fi network. Try again.

Axel F.

1) Try and Force Restart your iPhone EXACTLY as shown below and see whether that resolves the issue:

• Press and quickly release Volume UP button
• Press and quickly release Volume DOWN button
• Press and Hold the SIDE button until an Apple logo appears and then release the Side button (Can take up to 20 seconds. (DO NOT release Side Button when invited to Slide Power OFF). 

(2)  If the above does not work then - Follow the instructions in this article by Apple ➔ If your iPhone is Non-Responsive or Frozen and see if that helps.

(3)  If that does not help your phone might need service ➔  Contact Apple for support and service - Apple Support

Axel F.