Hello @Maksym2,
Welcome to the community!
Keep the phone on in case the owner tries calling it, if not what I did the last time I found a phone was take out the SIM card and put it into a phone I have access to then go to settings about phone and look for the SIM information you should see the phone number registered to the SIM card call the number and you should get hold of the owner and you can return the device directly to the owner.
