Is there a way to darken all the text in a pdf? I just want to slightly increase the weight.* Not all pdf viewers render the same. Foxit renders thicker than Okular. Adobe Acrobat renders the lightest. I want something which shall render like Preview on MacOS, which renders it very thick. Firefox and Chrome render it slightly blurry. So are some parameters which I can change in order to modify the appearance of a compiled pdf? I want to do it for an already compiled pdf, whose source code is not available.
*Many of the digitizations of the fonts, such as Times or Garamond, it seems, were designed from the metal sorts, and not from the printed output. The printed output is slightly thicker due to the spreading of ink. Thus, the digitizations are often anemic. the Same holds true for Computer Modern. Even though Computer Modern was designed digitally, it was created for viewing when printed, not on screen. And the original font offered 'modes' to modify the font according to one's printer. Unfortunately, all the vectorized clones of Computer Modern (except two modern ones) are very thin. This font is very popular when it comes to typesetting mathematical texts, the texts that I am most interested in reading.
Edit: Added a real world example in response to a comment. Take any document created using LaTeX. For example this unofficial reference manual for LaTeX2e: https://texdoc.org/serve/latex2e.pdf/0.