I don’t believe it’s possible to redirect a topic to another topic with a permalink. You’d end up with a topic that exists but is inaccessible (because visiting it redirects you).
What you could do instead is close the original topic and make the last reply a link to the new one. Or if you want to hide the original topic entirely you could archive it.
We keep seeing users try to abuse permalinks in this manner, therefore our UI is broken. How can we make it more clear what this feature is for in the UI @techAPJ? Can we generate an error when someone tries to generate an internal permalink?