Don’t forget to pin it this extension to use it where you want. For Google Search results, as leocg said, go to its Manage extension page to “Allow access to search page results”, and if you want to "Allow access on private pages".

I hope this helps.....

The problem isn't so much browsers as websites. If a website says they want visited links blue, the browser does that. An add-on like Stylus can override what the page says for visited link color (or text style, or anything else).