I created a blueprint that would change the color of the spotlight very fast but when i play test it , it just displays white. I dont know if i did anything wrong im just playing around and im quite new to blueprints.
when ever you have questions like this, post a picture of the blueprint 
we need to see whats going on to troubleshoot it.
Heres the blueprint
event tick is fired >every< frame, assuming 60 FPS your light is flickering through 60 changes per second, and as white light is just every color, it looks white. also, as far as i know “make linear color” uses 0-1 range, so 255 in all 3 will just make a very bright white unless it randomly hits something under 1,1,1