How big is the unit of Star Domain?

The previous question is not very clear. Stars, galaxies, constellations, nebulae, etc. Usually used to describe starry sky units. The concept of star domain seems to be rare in the scientific community, and there is no specific concept of size. Even the sizes of different stars and galaxies vary greatly, and some stars are close to galaxies, so it's hard to say. As for the latter 6 and above, including 6, this question is actually very simple, and it is estimated that many primary school students know it. Let me give you a simple example: "above 6" and "above 6" have been pondered and are easy to understand.