variable resolution frame renders?

Yeah, weird wording, but all my google searches show me is about the multires modifier. Thats not my issue.
You know how you can render an animation to images for each frame?
Well, id like those images to have different render resolutions(frame 1- 1000 x1000, frame 2 - 500 x 500, frame 3 - 1000 x 500)
Is this possible?

You cannot animate the resolution on the panels, but you can in the node editor.
One way is by using scale and go to a frame, change the scale, hover mouse over it and hit ā€˜iā€™ to set key frame.