In Discourse, permalinks are typically used to redirect from an old URL to a new one when migrating from another platform. They’re not typically used to redirect between topics within Discourse itself.
If you want to redirect users from one topic to another within Discourse, the best way to do this is to close the original topic and leave a note with a link to the new topic. This way, users who visit the original topic will see the note and can click the link to visit the new topic.
You can use permalinks to redirect one topic to another
Just make sure the old topic is in a public category, is deleted, and that you’re using an account to access it which doesn’t also have access to see deleted topics (so non-admin/mod or tl4 if you have tl4 delete posts and topics enabled).