Nikon Rumors has a nice summation of some of the better efforts to use the sizzle picture of the coming Nikon Z9 to conduct some size comparisons with the most recent Nikon flagship DSLR, the D6.

Comparison on Site by “MB”a

The upshot is that the new camera is slightly smaller, but not by much. All told there is about a centimeter lost in both height and width. The information was estimated based on pixel counts comparing the Nikkor Z 24-70 f/2.8 lens, which has known dimensions.