Um, I'm pretty sure a 24mm shot on a full frame camera will look the same as an iPhone shot, but only if you crop the full frame shot (ignoring pixels counts).

Yes, you could get the same photo of the guy in the centre on the iPhone, but only by zooming in and cropping out everything else. I guess if you REALLY wanted you could run back, and zoom in. Better get a tripod to hold it steady since you're zooming in then.

So anyone but an expert will shoot with a much shorter lens when using the iPhone.

This is how crop factors work unless I'm really mistaken.

Please note that I specifically said “equivalent focal length”.

A 24mm equivalent will have almost the exact same perspective on any sized sensor, because that’s what equivalent means. It’s a relationship of sensor size to actual focal length.

A 16mm on a 1.5x APs-c is a 24mm equivalent on a 35mm. The iPhones base lens is something like 1.5mm but when related to its sensor, it’s roughly a 24mm equivalent.

There’s no cropping that needs to happen.