Iphone hard reset

I found my child with an Iphone 7 that they should not have had. I handed it over to my wife and left. My wife says she tried to access it a few times but it did not work. She then got a passcode (a 6 digit number) from my child but says after she entered it the phone did a hard reset. I returned to find the phone going through a reset and then a hello screen. This all occurred within about 10mins. My child denies all knowledge.

Is it possible to reset an iPhone by entering a code or could a third party be involved? Any ideas?