None of these cameras make better images than the D3300. What they offer is more control so with skill it allows a user to get better images based on manual control but at the same time, unless using better technique images can be worse.
The D7200 has a lot of features that are shared with higher end enthusiast camera.
for close up work, Full frame has better close up and macro lenses. The kit lens on the Z6 24-70 f/4 is not a macro (micro in Nikon speak) but has excellent close working optics, better than any F mount crop macro lens. A dedicated macro lens will be full frame.
If you think this new purchase it the last camera you every buy, the D7200 would be a good bargain since they are going for $750 but the more capable easier to use Z6 just has had a $300 price reduction. The new price is $1699 body only.
The D7500 is $799 body only so that is a strong contender if you want to stay with current lenses.
The $799 price of a Z50 which is 80% of the Z6, smaller and lighter than any of them but with excellent image quality and manual focus using the EVF on Macro lenses. Manual focus is the normal focusing method with macro lenses. But in auto focus, for such subject the Z50, 6, 7 will focus more accurately than any DSLR. -
If you are into action wildlife shooting, saving for the D500 is very good for that style of shooting.
My first question is always, "what would the new camera do to make current photos better?" The answer usually is " I just want something new" The D3300 is a very capable camera, it has a sensor that is better in all ways than the top pro cameras of 2005 and no one complained about image quality. Look through almost any photo gallery and see great images from all eras and with equipment less capable than what you have now. The biggest difference is lighting, or tripods, not bodies. A d90 from 2008 12mpx is still capable of great portraits that would not be told from newest cameras.
The assumption that cameras make a big difference in image quality just does not stand up scrutiny. The differences is almost always in creative use of light and composition. Composition if free and lighting is cheap but both require learning skills in using them to paint the story you want to tell.