Can Preview (mac) alter the background and text colors of pdfs?
Solution 1:
That feature does not appear to be implemented in Preview.
Solution 2:
If you are just trying to make PDFs more readable, you can try inverting your colors by pressing [CONTROL] + [OPTION] + [COMMAND] + [8]. Note that this inverts the display colors system-wide, so it may not be the best option, but it does make reading B&W text easier.