This is a plugin I found recently and really enjoy. It gives you the opportunity to redirect several webpages to alternatives. For example Youtube to FreeTube or Piped. If I search for youtube in Firefox, FreeTube automatically opens and shows me my feed. I like it, I use it, I can recommend it.
You can exclude
https://youtube.com/from redirection, that way, the YouTube homepage won’t be redirected, but all videos will be.