Round RGB rope light is available in incandescent and LED - just do a search and you'll find several vendors.
Lots of it is oriented to 120 mains power, so I suspect a LE could control (dim) it as 3 AC channels. You can thinkof it as just an incan or LED string like you get at K-Mart except housed differently.
But like those forms, it's limited in where you can cut it since the bulbs/LEDs in a segment must add up to 120v FOR EACH COLOR. However, the big sites sell it in 150' rolls and you are expected to cut segments and attach connectors.
There's also DC stuff if you look around. You'll have to explore that.
And yes, the R, G, and B are separate lights, so it does not do color blending like true RGB lights; it's more like a Red + Green + Blue multistrand.