Issuing man route will pretty much tell you what you need to do, but for the sake of completeness it should be something like route add
FreeBSD Set a Default Route / Gateway - nixCraft Aug 30, 2017 Set DNS and Default Route in PFSense from Console - djlab.com Apr 12, 2012 Pfsense routing between subnets - Networking Software Apr 14, 2018
Nov 30, 2019
The Best pfSense Box (Updated 2019) - The Geek Pub Dec 15, 2019 networking - How to add route after connecting to openvpn Issuing man route will pretty much tell you what you need to do, but for the sake of completeness it should be something like route add
# Add Internal Net 2 as a persistent static route static_routes="internalnet2" route_internalnet2="-net 192.168.2.0/24 192.168.1.2" The static_routes configuration variable is a list of strings separated by a space, where each string references a route name. The variable route_internalnet2 contains the static route for that route name.
ifa_add_loopback_route: insertion failed | The FreeBSD Forums Dec 19, 2011 [pfSense] Adding Routes | The FreeBSD Forums