I simply change the font settings in LXQt Appearance Configuration. This generates a Fontconfig file in ~/.config/fontconfig/fonts.conf, which most applications respect. One exception is my favorite terminal emulator Kitty, which can be easily patched. In freetype.c, change the last line of get_load_flags() to "return base | FT_LOAD_MONOCHROME | FT_LOAD_TARGET_MONO;"

I assume other desktop environments support something similar.