So what I am trying to achieve is to draw 2d quadrangular bounds on a screen and then rotate plane game object to fit those bounds. Here’s the screenshot of the bounds to give you a better idea:

OK as @Bunny83 points out no one can do that because we can’t set the scale of the object.

But how about this…

We can get the X and Y as it’s just how far left/right and up/down the screen it is what we can’t work out is the depth.

However we could do some calculations on the distance between the points compared to screen height and then decide if say 3/4 of the screen that equates to 2 deep and half = 4 deep.

This can be done with a calculation to divide 1 by whatever the fraction of the screen height is. The smaller the height of the screen % used the bigger the number for how far away the object is.

So if we can pinpoint X and Y and calculate Z based on our rule you should be able to get the distance between these points. You should be able to create your plane and set it’s corners that way.