iCloud activation lock from previous owner

Hello to everyone.

I wish can get your support to the following problem.

I got an iPhone 11pro max as a gift. It has an iCloud activation lock and is in lost mode. I can’t use this phone, cause can’t find the previous owner to ask for the Apple ID and password to reset the phone.

I tried to get the proof of purchase documentation from whom I got phone as a gift, but they purchased the phone from a stranger, not from store and didn’t get any documentation . So I can’t get a support from Apple too.

Now what can I do, is there any solution?

Thank you