can cubemaps be used for atlasing?

Hello!

I've read that developers of a game called Company of Heroes used a "cubemap atlas" (6х2048х2048) for storing all the little pieces of textures for effects in one place and rendering it in one draw call. Is it possible to use the same trick in unity for having atlases larger than 2048x2048 or will it fail because cubemap is still a bunch of 6 textures for the engine?

thanks