AirDrop is quite different though. Because presumably they are doing this to anyone nearby with a female-looking name for their deceive.
Don't get me wrong, unsolicited dick pix are bad.
But I think it's an aggravated situation when they are sent just to anyone nearby.
The person had to be fairly close though. So when the notification comes up (which contains a pic preview so you damned well have to see it) screenshot, and sag loudly "I cannot believe I have been sent an offensive communication. I have screenshotted and will report to the police. Anyone else want to see it?" and let anyone nearby see it.
If it happens to your DD, train them to do the same, but announce loudly "Someone's sent an indecent image to a child. Anyone know where the nearest police station is"