Question General purpose HDRP shader

Hi guys,

Is there a way to achieve a general purpose toon shader that can be applied either to the whole scene or to be added to any model on a scene? I can see that shaders need materials to work, and then these materials are semi-hardcoded on their exact looks - but i'm wondering about being able to apply an additive shader - as in leave the base material intact, and then apply another pass on it to change it to toon mode.

Alternatively, how could i reference a secondary material/texture/variable on the same model the shader is applied to?

Thanks,
Primoz