Restarting iphone

Ask the person who sold you that iPhone.

If the seller is not helping, you got scammed.

Activation Lock is a theft deterrent feature with no bypass or workaround.

Without the owner's authorisation (Apple ID & password), no thief or anyone including you can re-use the device.

Get your money back.

It's undoubtedly activation locked.

There is no way to bypass the activation lock. Only the owner of the account used to lock it can remove the activation lock.