You need to show an example. But I assume the answer is NO. As PP operated on GBuffer, that is basically a bunch of images, there is no geometry at this stage.
The most prominent “effect” of PS1 was the lack of position precision. So the vertices of the meshes were snapping to certain rounding of the world coordinates. It can be achieved in the Vertex shader of the model, but not in the PP. (i think you can find examples of that shader on the web).