You can use the post-process effect on a render target. In your Scene Capture 2D object, change the Capture Source from “Scene Colour (HDR)” to “Final Colour (LDR)”. You can also apply a different cel shader effect (or any post-process effect) to this scene capture 2d object only. You can switch to back to the HDR source to use ONLY that post-process effect.
The camera and settings:
The resulting rendertarget:
