It’s confirmed folks! Olympus registered a new camera model with built-in grip at Fccid.io. And the agency reports the exact size of the camera:

E-M1X is 144.37 x 146.765 x 75.345mm

By Comparison this is the size of other cameras:

E-M1 Mark II: 134.1 x 90.9 x 68.9mm

Canon EOS-1D X Mark II: 158.0 x 167.6 x 82.6mm or

Nikon D5: 160.0 x 158.5 x 92.0mm.

via Nokishita