First off, the 200 micro has a magnification ratio of 1:1. That is pretty much standard among most macro lenses. The 200mm is somewhat unique in it's long focal length. That gives you an advantage in working distance, but no advantage in magnification over, say, the more common 105mm micro.
Looking at the data on the image you posted, I see that you focused at .89m. The 200mm has a minimum focus distance of .5m. Focusing at or very near the minimum will give you the maximum magnification. The easiest way to achieve this is to manually focus the lens at minimum focus distance, then move the camera closer to your subject until you are in focus.
You have a D850 and apparently a D7000 as well. With the crop frame sensor on the D7000, the camera only uses about half of the full image and has an apparent magnification of around 1.5:1. You can do the same with the D850 by cropping the image in post. If you crop to around 1.5:1, you will still have around a 24 MB image, whereas the D7000 will be 16MB. I would go with the D850 and crop in post for max magnification. You should be able to push a little beyond half the image in post.
If you want more magnification than this, you can add extension tubes, a bellows, tele converter, or diopters. They all have their pros and cons. Another option is to get a macro lens designed for 2:1 magnification.
Here is an image taken with a Nikon 105mm micro lens. It was shot at near minimum focus distance and cropped from a 45 MP image.
