pfSense automatically listens for connections to the settings page from all interfaces, but only opens the firewall by default on the LAN interface (you can disable the "anti-lockout" rule in settings, but be careful). If you wanted to access the settings page from the WAN, for example, just add a rule to the WAN to allow access from anywhere to the WAN IP address, protocol HTTPS (port 443) TCP, and you will be able to access it remotely. Same is true of any other interface, add a similar rule for access to the interface IP, from any or specific IPs as desired. Or, add explicit block rules if you want to or if you've opened it up with other rules. I also tend to change the listening port to something other than 443 so I don't interfere with port-forwarding of HTTPS and am on a non-standard port (less likely to be target of random scans from Internet or guesses internally).