Setup SSL within Postgresql-variable configuration node doubt

Having to secure the Node-Red / PostgreSQL DB connection from sniffing I'm wondering if it will be sufficient - after configuring in the Postgres configuration file "SSL" option to "ON" and specifying the correct path (and permission) to .pem certificates on the server hosting the Postgres DB - to check the "SSL" checkbox in the Postgresql-variable configuration node.
On the client side, do I have to specify in some kind the certificate or it's enough to declare it on the server-side??