To setup my new iPad pro based on my existing iPad pro I used the quick start feature (https://support.apple.com/en-us/HT210216).
At first the quick start screen did not appear on the old iPad.
I fixed this by enabeling Bluetooth on the old iPad and then rebooting the new iPad by pressing and holding the power button and the up volume button at the same time.
The iPad then powers off. Wait for 10 seconds then press the power button to turn it on. Now the quick start screen appeared on the old iPad.
Also make sure you don’t have your iPhone nearby, because then it will try to start the quick start from your iPhone.