I'm assuming you don't yet have a YouTube rep? That is important for this. Feel free to correct me if you do.
It is possible to do what you are asking, or something close to what you are asking with vanity url's.
this allows you to point another url to the channel. For example, your desired url can point to the correct channel, but you would be left with 1 channel and 2 urls that point to the same channel.
For instance youtube.com/freddiew and /rocketjump go to the same exact channel.
There's also instances of this with companies that have UK and USA urls that all point to the same main English channel
I think this feature first "released" in 2013/14. Unfortunately, this is a feature left exclusively for people with connections and even they sometimes don't get approval. If you have a large channel and/or a YouTube rep, you should ask them for help with this. Otherwise... keep growing your channel until you get there? or accept that it's not possible for the most part.