Mastering.com walks through Logic Pro's Modifier, a tool for mapping a hardware MIDI knob directly to any plugin parameter without touching the mouse.
Using Learn MIDI and Learn Plugin Parameter, a knob gets tied to a tape delay's wet/dry control. Scaling and offset settings narrow the range so the knob only sweeps between subtle values, like 4% to 77% wet, instead of the full 0-100%.
Once the mapping feels right, turning the knob live gets recorded straight into the track as automation, capturing a performed effect rather than hand-drawn curves.
The Through setting lets a new mapping stack on top of a synth's built-in mod wheel behavior, so one movement can control both a custom parameter and whatever effect is already baked into the instrument, opening up more layered, expressive automation than either control alone.