Does Beeper Support IRC?
If you're looking to connect to IRC, you can run your own bridge and connect it to easily connect it to Beeper: https://github.com/beeper/bridge-manager/wiki/Heisenbridge.
There are also public Matrix bridges to some IRC networks available: https://matrix-org.github.io/matrix-appservice-irc/latest/bridged_networks.html. However, the public libera.chat bridge no longer allows joining arbitrary channels, so self-hosting is recommended instead.