Stretch shape size on one side only

[Calai]

Say I have a square and I want to extend nothing but the left size. The way I've found to do that is moving the anchor point to the other side first. If not, I would increse the size of the whole shape altogether.

Isn't there a hold down CTRL type of deal before clicking and dragging? It seem too much of effort having to move to anchor point first.

[ShiveringCactus]

Not that I am aware of, the closest thing I can think of would be to set an expression to the anchor point and save it as a preset.

var width = thisLayer.sourceRectAtTime().width;
var edge = width/-2;
[edge,value[1]]

But with shape layers, each shape also has it's own transform properties, which gets frustrating.  I made a script to centre shapes on the layer position.  You're welcome to try it:
https://www.dropbox.com/scl/fi/gm38jcnmwndn2sp19dfsc/Centre-Shape-by-ShiveringCactus.zip?rlkey=kdvcp...

In both cases, using a free tool like FX Console makes applying them a single click.

[Calai]

Would you elaborate on this FX Console? 

[ShiveringCactus]

FX Console is a free tool from Video Copilot:

https://www.videocopilot.net/blog/2018/05/fx-console-updated-to-v1-0-3/

It contains several features - such as a really easy way to take screenshots.  And it also includes the ability to set shortcuts to apply presets.

[thepixelsmith]

Scaling in AE, is always based on the position of teh anchor point unlike in other programs there is no keyboard modifier to shift scaling from the center or opposite corner.