Distance independent size of gameobject

As title says I’m trying to adjust scale of 3d object so it “stays” the same size wherever is positioned.I’m using perspective camera and (see picture) cube is getting larger when it’s moved up or down. Basically camera position is at x,0,0 , x being x location of cube so distance camera to object is greater when cube is not in the middle of screen.Anyone has idea how to scale object properly ?
TL;DR How to scale object at event tick to stay same size if further away from camera