I found an iPhone in a taxi

No, nobody here (these are user community forums) knows anything about other people‘s property. And Apple does not get involved with lost or stolen personal property at all. Either turn it in to the cab company‘s lost and found, or the police. There is no way for you to find out anything about the owner yourself.

Turn in it to your local police station.

Hi

Ask the Taxi company if anyone has lost an iphone?

Only return to the owner if they know the passcode & mobile number.

Or hand in to the police.

Cheers

Brian 🇬-1F1E7;