This assumes that you have a basic knowledge of subnetting and NAT.

This is where you have one public IP and multiple LAN ips.

The WAN interface can be DHCP or static Set a static IP on the LAN

Set Automatic outbound nat

Done

You do not have to specify static WAN ip but you really should! In this example the pfsense is on the blue team network (10.20.0.0/16) with the static IP 10.20.123.1/16

Set static IP on the LAN

Go to the NAT settings. Firewall > NAT > Add

Create a new rule mapping the first external address (in this case 10.20.123.1) to the first internal address (192.168.1.1) and use the subnet mask for the internal network (24)

Finally you need to make the pfsense respond to ARP for those IPs. Firewall > Virtual IPs > Add.

Done