How do I find the dimensions of a cube in terms of (X, Y, Z, Width, Height, Depth)?

X,Y,Z is stored in vector3 field gameObject.transform.position(.x, .y , .z) (dependent of where pivot point is)

width,height,Depth is in gameObject.transform.localScale(.x,.y,.z)

If you want to get them in your nomenclature (X, Y, Z, Width, Height, Depth) like for rect,

You have to have the pivot point in the corner. The default unity cube will have it in the center. Hence you will need to shift by half of scale, For instance your X will be gameObject.Transform.position.x - gameObject.Transform.localScale.x/2 etc.

Transform.Scale should do it, surely? If you’re using a unity primitive, taking unity units as meters, a standard cube is 1m x 1m x 1m.