For those that want or need the extra privacy. Learn more about Tor at Tor Project.
You will need a Jabber App that supports connecting through a SOCKS proxy. Known apps that support proxies are Gajim for desktop and Cheogram for Android. You will also need Tor (or Orbot for Android) from the Tor Project running.
For the proxy settings in your app once you have Tor running, you want the protocol set to SOCKS (if the setting is listed), hostname set to localhost, and for port standard Tor defaults to listening on port 9050 while Tor included with Tor Browser defaults to port 9150.
Afterward, for the Jabber account you will need to set it to use a custom hostname and port. The Onion Service hostname is r2honyf66tg6xmz3qybi6wvkpvfa5gspouujh7w5qa3llf62leytsaqd.onion and the port is 5222.