You've designed a spectacular Christmas light display and you realize that you need to gradually ramp up and down a few strands of mini lights as the tension builds to the high point of either Silent Night or Grandma Got Run Over by a Reindeer.
Now, you're wondering what kind of lights can be dimmed and ramped up with an increase or decrease of the voltage.
Here is the "Yes" answer:
Incandescent Mini Lights are dimmable
Traditional incandescent lights operated under a very simple premise. Heat a filament in the presence of an inert gas and the heat of the filament heats up and produces light. The amount of current in the filament dictates the brightness of the bulb.
Ramping the voltage, ramps the current which controls the brightness of the bulbs.
So, traditional mini lights - or just about any kind of incandescent lighting product is a good choice for projects where you need to dim or brighten your display.
Here's the bad news:
LED Mini Lights are not dimmable
The lights produced by LEDs (light emitting diodes) is created by semiconductor based technology. The light comes on when you hit a certain voltage threshold and goes off when you go below it. Semiconductors are all about 1's and 0's.
While you can flash most pre-wired sets of LED light strings on and off, they cannot be ramped up in brightness by changing the input voltage.
(Note, flashing LED light strings on and off will reduce their maximum lifespan.)
On a quick side-note, use an outdoor rated surge protector for all of your LED Christmas lights. Just like you'd never think to plug a computer directly into the way to protect it's internal circuitry, think of your LED lights the same way.