Hello trinita and welcome to these forums. You'll find many helpful people here and a lot of useful information. Make sure that you:
I think that that control is done by MIDI CC messages, not by MIDI notes.
If control by MIDI CC messages is what you are looking for, then
-- all plug-in parameters can be controlled by MIDI CC messages using Reaper's Automation
-- for some plug-ins, the GUi may have some controls that are not plug-in parameters, those cannot be controlled,
-- for some plug-ins, the devloper has implemented a system of controlling it directly using MIDI CC messages, with no need for Reaper's Automation.
-- for a few plug-ins, MIDI Notes can be used to control some of the controls
Here's a thread about both methods:
https://forum.cockos.com/showthread.php?t=180970
Can you post a few specifics - which plug-ins and which controls? What MIDi controller do you have. Then some users of those products can give you more focussed guidance.