Help plz! How can I isolate materials so that they are not affected by my post-processing materials?

Hello! My name is Victor and I am currently close to finish one of the last projects of the master I am studying. The thing is that I would like to isolate the foliage and leaves materials from the outline belonging to the postprocessing material, because, as you can see, the black color messes up the vibrant colors, the saturation and the colorfulness of the scene. I would like to keep the outline shader on the rest of the objects, but I don’t know what to do to apply it on some and isolate others. Please, could someone help me? Thank you so much in advance!