Blocking youtube channels from my phone
There are many YouTube channels which pop up on top search results but are just clickbaits. YouTube won't allow to block channels. So it would be great if NEXTDNS does something.
You can search the term "Assamese G.K" and 90% of the search results are NSFW. I don't feel safe for my child.
It's not what you're looking for but here is the solution to your problem.
On the Parental Controls tab, there is a YouTube Restricted Mode, it explains what the switch is for but it's basically safe mode for YouTube, it restricts vulgar or general videos deemed not safe for kids. This should solve your issue.