Capacitors store energy up to their capacity, not being snarky with the tautological statement, that’s what they do. So yes they can slow or modulate electron flow. The simplest pulsing circuit you can make uses a capacitor.

My own personal projects these days include work with super-capacitors to make battery-free solar projects.

This stack exchange has a good discussion that relates here:

https://electronics.stackexchange.com/questions/380104/how-to-pulse-an-led-for-a-second-with-just-a-single-switch-resistors-and-capaci