unable to turn off new ipad pro 11''

To completely shut-down your iPad, you have two options.

From Settings:

Settings > General > Shut Down

Alternatively, using the Sleep/Wake (Top) button, press and hold this button until the Shut Down slider appears - then slide your finger along the slider.

I hope you find this to be helpful in resolving any issues that you may have.

I found that on my iPad Pro , v13.5.1, I have to push both the top button and one of the volume buttons to turn off. But I find a difference between the up and down volume button in how it turns off. If using the up button, the battery will inexplicably lose power by as much as 50% in a 24 hour period. With this method, when I power on, the Apple logo will appear immediately. If I use the down button to power down, the battery does not lose any power in that same time frame. With this method, when I power on, I must hold the top Botton down for at least 5 or 6 seconds before the Apple logo appears. Looking at the battery graph shows there are no processes running during the off period in either case. This is something that started with iPadOS 13.5. Go figure???