Can I use the volume (increase/decrease) volume/wah pedal to switch between effects?

USING THE VOLUME (INCREASE DECREASE) TO SLIDE TO AND FROM ONE EFFECT OR ANOTHER:

          Like if I have a clean sound on my guitar and no reverb when the pedal is cocked then bringing it back to have a full reverb sound or clean effect going to distorted or to have the clean sound on the wah and distorted on the volume.

USING VOLUME/WAH TO SWITCH BETWEEN 2 EFFECTS:

        I know that you can assign things to the outgoing section and that is confusing to me.