NodeMCU + Blynk

Good afternoon people !
I need some help, I’m using nodeMCU and Blynk and I can’t mount a test for which I’m building a project.
I’m gonna explain:
I want to create 4 buttons on Blynk for example D5, D6 and D7 ports to light an RGB led, each of these ports lights a color. (so far so good) I got it.
My challenge now is:
In the fourth button I wanted when I put it in ON mode (switch) on Blynk I wanted the leds to light up one at a time flashing until I changed that position to OFF.
can anybody help me?

Are you using Blynk Legacy or Blynk IoT?