I am updating ios to 14.6 and it has been preparing update for more than 2 hours. Is this normal?

Something has potentially stalled. If your iPad is unresponsive, you will need to restart your iPad:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.