What to do if you receive an iPad that has someone’s else Apple ID ?

Return it if possible. Eventually you will experience an Activation Lock.

You need the Apple ID and password that was used when the device was first set up. If you don’t know that, you can’t remove the Activation Lock.

If this is a used device, the previous owner needs to go to https://www.icloud.com/find/ and erase the device, then remove it from their account. If they won't do that, the device is useless. Apple won't unlock it.

Turn off Activation Lock - Apple Support.   *