I cannot find the owner to unlock the iPad

If it has Activation Lock, neither we, just users like you, nor Apple can help you, sorry.

If possible, return that device and ask for a refund (since it is useless to you).

If you mean some different type of "lock", please better specify your situation.

Regards

Giulio

Your options are limited...

Here are the Apple support pages that outline the Activation Lock - and the only mechanisms by which it can be turned off:

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Turn off Activation Lock – Apple Support

As you will discover, unless you are the owner of the AppleID that was last used to activate the device, or unless you can secure the cooperation of the previous owner, you’ll not be able to defeat or bypass the Activation Lock. Without documentary evidence that you are the original owner (such as sales receipt showing the serial number), Apple won’t assist - and nobody here will be able to help you.

The All Too Common SAD Reality of Buying … - Apple Community