When somebody finds a lost phone, the device doesn't usually reveal who its owner is, especially if it's locked with a passcode. However, it's different for an iPhone or iPad equipped with the voice assistant Siri. In that case it's quite easy to find the owner.
You simply hold down the home button till Siri activates and then say aloud, "Who owns this phone?" or "Whose phone is this," Siri will respond by giving the owner's name and displaying their contact information.