You could use Consent-O-Matic https://addons.mozilla.org/en-US/firefox/addon/consent-o-mat...

It already pushes the correct "Reject" button for you on a lot of sites (not all; it works based on rule lists)

I used this for a bit and then some sites would just not work. I get it. It’s a hard thing to do and I admire it but getting blank result is far more frustrating than clicking accept each time.