first hide the layers of everything you don’t want to put the effect on and make a new, blank layer over everything else
then press command+alt+shift+E to make a merged copy of those visible layers. double clicking that layer will make the “layer style” window pop up, and you can deselect the G and B channels
use the command+T hotkey and your arrow buttons/mouse to move the top layer and get the effect! you can move it as much as you want (here i moved it farther to the right)
The father’s artistic talent is clearly on display here, but I’m actually really impressed with this kid’s wild imagination. Many of his drawings are both conceptually unique and coherent.