Is it possible to use a UI mask to mask out something from another Canvas?

Is it possible to use a UI mask to mask out something from another Canvas?
If so, how?
I have two world space canvases. One is for the player (the one with the mask) and one for an enemy.

I don’t know how to mask something else in a canvas, but if you want to display the things under, why you don’t do a background image for the panel with a trasparent section in the center?

If you want to display on the canvas only some objects in the background, you can modify the layer of the object to display, or change the shader of the object as well