AFAIK there is nothing built into FreePBX to do a redirect. If you want it, see
IMO, it’s better to just disable the HTTP port(s). When you tell your users how to access UCP, the URL you supply should include the HTTPS. Access to the admin GUI should be limited to very few specific IP addresses. In an emergency, if you have to access it from somewhere else, use SSH port forwarding, a VPN, or e.g. TeamViewer to a workstation that has access.