Activation Lock

it's a theft protection

Turn off Activation Lock - Apple Support

and or https://iforgot.apple.com/password/verify/appleid

or

Genius Bar Reservation and Apple Support Options - Apple

If you are the original owner AND if you have the proof of purchase, make an appointment at an Apple Store and they should be able to help you.

Shouldn’t be this case there’s no way to bypass activation lock, except knowing the credentials that were used to activate that device.

Regards

Giulio