https://docs.netgate.com/pfsense/en/latest/firewall/ethernet-rules.html

More traditional way of accomplishing this would be put all the devices you want to filter on their own vlan, so then doesn't matter what IP they have - any device on this network is going to use the rules you set.

Or you could setup reservations for these mac addresses you know so they always get the same IP, and then create an alias with these IPs in that you apply your block rule too, etc.