I added a second handle to my YouTube channel this morning.
I can access my channel with either handle, but, if I navigate to youtube.com/handle , I don't see the new handle, I only see the original one.
I don't know how if multiple handles are supported, and how many, or if my new handle will replace the original one within a few days at which time the original handle will no longer work.
I'm also not clear if it's possible to transfer a handle to a different channel.
My research returned conflicting information:
Each channel can only have one handle. You'll see handles in places like comments, mentions, and in Shorts. Your handle will show in more places over time. You can also use your handle outside of YouTube to promote your channel. https://support.google.com/youtube/answer/11585688
Creating a second channel is a great way to keep your content organized. https://www.adobe.com/creativecloud/video/hub/guides/how-to-start-second-youtube-channel