For me the most important extension is uBlock Origin. It's worth switching to Firefox for this alone.

Without your ublock origin browsing the net is quite horrible these days

Youtube is virtually unwatchable without it. I honestly have no idea how most people cope. Truth is, even with an adblocker there's so much rubbish on the page that gets in my way. Invidous is much better but it's too unreliable.

Sites that autoplay a video, which follows you as you scroll are the worst.

I like the Unhooked extension. You can select which parts of YouTube you want to remove (e. g. Shorts). My start page is empty, I need to visit the channel pages to watch their videos.

Or for real control, uMatrix (yes there are madmen like me still stubbornly hanging on)

that + NoScript. That latter is a must for me.