Disable external free VPN Service
Hello, i would linke to block all incoming and outgoing connection to free or paid VPN services such expressvpn.com
Which rule to add into the pfsense firewall ? any advice?
There isn't any way to express that in a simple rule. You'd have to find a list of those providers and block their addresses/netblocks. You can likely leverage pfBlockerNG to get most of the way there.
A lot of them use non-standard ports, or overload things on common ports, so you can't reliably block them based on anything other than the destination address, and even that will be tricky and akin to playing whack-a-mole. New providers pop up all the time.