Indeed, there is no magic, just use a Lens:
It is a 37mm thread Circular Polarizing Lens Filter, used to use on Digicam and DJI Drones, GoPro Action Cameras...
Now you can use on your smartphone!
The little magic probably is the attaching tool:
If you got a case mount cover, you can even use on a smartphone too:
It is availabe at www.DCKina.com