nano /usr/local/etc/pkg/repos/FreeBSD.conf
And set "enabled: yes"
pkg install obfs4proxy-tor

pkg add https://pkg.freebsd.org/FreeBSD:14:amd64/release_2/All/obfs4proxy-tor-0.0.14_17.pkg

nano /usr/local/opnsense/service/templates/OPNsense/Tor/torrc

ClientTransportPlugin obfs4 exec /usr/local/bin/obfs4proxy
 
Bridge obfs4 IP:PORT KEY cert=CERT iat-mode=0
Bridge obfs4 IP:PORT KEY cert=CERT iat-mode=0 
Bridge obfs4 IP:PORT KEY cert=CERT iat-mode=0
 
UseBridges 1
...

/usr/local/etc/rc.d/tor restart