help to scale bones

[Bossy]

 

hello I have a problem rather a doubt someone knows how it could be done to make some parts of the body of the player, I know it is done with shaders but someone could pass me a script or some way of doing it since I do not know anything about shaders or pass an editable script, please 

 

for example:

https://www.youwwwube.com/watch?v=sOTDHReX2rs