If you can’t, it’s probably because no one’s tried yet. (30x30 display’s pretty small, though, so I don’t know how playable it would be.)

Not unless they’re complete boneheads (which, admittedly, is not impossible). If they do that, they effectively lose embed-video-in-external-sites functionality, and that might just be enough for unpaid content creators to dump the platform en masse and cause their effective monopoly to crumble. The content creators who are actually making decent money may never leave entirely, but if another viable platform comes into existence, I bet most of them would mirror to it.

No extension—even Netscape 1.0 had most of this stuff built in. I use Pale Moon as a primary browser, but the settings required still exist in modern Firefox, under General > Language and Appearance > Contrast Control and General > Language and Appearance > Fonts > Advanced. Note that although the font labels may say “Serif” etc., Pale Moon at least doesn’t care what you put there—you can set “Serif” to a sans font if you like, or vice-versa.

Of the Chrome-based browsers I have lying around for work and emergency purposes, Vivaldi has the font settings under Webpage, but doesn’t have full webpage colour settings (although you can force a dark theme, which might be enough). Chromium has the font settings under Appearance > Customize Fonts, but lacks anything that looks like useful colour settings.

If you’re looking for browser extensions that will restore the colour-forcing functionality for Chrome-based browsers, “Accessibility” is one category to look under.

Like what are the drug cops even supposed to do now, arrest Facebook?

We can only hope.

My browser is set to override the colour scheme of all pages I visit. It breaks the odd site that doesn’t know how to present image content correctly, but I consider that an acceptable tradeoff. It also forces a specific font and minimum font size.

If the bots are required to have paid transit passes and if they’re confined to off-peak hours when the subways aren’t full anyway, this could actually be a net win for mass transit: they’re putting money into the system while consuming relatively few resources, so the bots can fund improvements that benefit humans.