When applied to a corner pinned layer, it creates a new corner pin effect (you'll have to disable your own corner pin effect) and adds a slider control. Tweak this slider control and you'll see you can 'scale' the corner pin effect while maintaining the same shape (the four new segments remain parallel to the old ones). I'd like to see this kind of control built in the corner pin effect.
I'm sure that the preset must have an expression in there somewhere, if some kind soul could just post the maths behind it, I would be super greatful.
I had to scale up a corner-pinned layer and stumbled upon this old preset. It still works in After Effects CC, but it performs a parallel scale. Unlike a perspective scale, it moves all corners by the same distance from their original location. For small adjustments, this might work, but if your camera angle changes significantly, the scaled objects will start floating. Therefore I looked up the math behind it (actually the geometry, not the math) and created this animation preset that scales a Corner Pin effect not in parallel, but in perspective:
Corner Pin – Scale in Perspective
Where to put the .ffx file
Mac: Macintosh HD ▸ Users ▸ Your user folder ▸ Documents ▸ Adobe ▸ After Effects 2020 ▸ User Presets
Windows: My Documents\Adobe\After Effects CC 2020\User Presets
How to use
Have a scene with a layer using the Corner Pin effect, working correctly, but too small
Disable your Corner Pin effect (but leave it where it is)
Find the preset in the Effects & Presets panel
Drag the animation preset onto your layer (it creates a second Corner Pin effect that references the first one via expressions)
Voilà, your layer should have 3x the width and 3x the height than before
Unlike the original preset, this one doesn't have a slider to adjust the scale. I recommend using a precomp to scale your objects.
If you use it, I would be glad if you drop a note here to let me know if it works for you. Feel free to enhance the preset.