/diy/ - Do It Yourself

I'm still reading this so you know but there's a lot to take in here so responding will be slow.
Aside from an long overdue thanks, I also want to ask something else. Is there a component you can put in to suddenly lower or increase resistance in a live circuit?
Like say for example if you were to put that part and a capacitor in the same line and drop resistance when the capacitor is discharging would it make for a stronger discharge?

I didn't say it sooner but forgive me for not knowing the lingo. I don't typically have anyone to talk shop with.