I can’t turn off my new ipad

See instructions below from Restart your iPad - Apple Support

How to restart an iPad that has Face ID

1. Press and hold either volume button and the top button until the power off slider appears.
2. 

1. Drag the slider, then wait 30 seconds for your device to turn off.
2. To turn your device back on, press and hold the top button until you see the Apple logo.

How to restart an iPad that has a Home button

1. Press and hold the top button until the power off slider appears.
2. 

1. Drag the slider, then wait for 30 seconds for your device to turn off.
2. To turn your device back on, press and hold the top button until you see the Apple logo.

Can't restart?

Learn what to do if your iPad is frozen, doesn't turn on, or doesn't respond.

Hold the Power and Volume up buttons at the same time until you see the swipe to power off, swipe and voila, your iPad will power off.