Do the MonoBehavior Scripts "OnMouseEnter/Over/Exit" only work for game objects that they are attached to?

Hi, I've been trying to get objects in my scene to "highlight" by changing the material to a different color when my mouse hovers over them. I cam across the scripts "OnMouseEnter()" "OnMouseOver()" and "OnMouseExit()". I'm using them in a script component on a canvas meant for Raycasting. I thought these functions would be called whenever I hovered over any collider within my scene, but as I go through the API it is beginning sound like these scripts only work for the game object they are attached to. Is this the case?

Is there a better way to go about making assets highlight when I hover over them while the application is running?