A lot depends on how you want to view the images you capture.
Printing large hi-rez images requires the stupid amount of megapixels.
Most people view images on the PC, mostly 1080p format low rez(now). Then if you want them cast to a 4k TV the format requirements change again.
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Printing A4 300 DPI 3508 x 2480 (large A3+, pages size in inches x300)
4k rez specs are: 3840 x 2160
That's the minimum number of pixels you need to print or view at those standards. The trade off on the number of pixels is in pixel pitch, which is the size of the pixel sensor. Larger sensors work better in low light conditions, smaller sensors tends to capture action shots better. Generally.
You can see the little A4 print is using nearly the same rez. as a 4k TV, not bad for a 1990's standard home printing format.
Good site for camera compares, the D610 is a good base, pretty old and well inside of your price range. If you're patient and can check the goods gumtree can be a good place to buy. (I'll second the Z5/6 the full spectrum 6 looked awesome, made you understand why insects use various wavelengths.)
https://www.digicamdb.com/compare/ni...-sony_a7s-iii/
Much like telescopes, try and join a photography club for long enough to try and get some hands on advice and experience.