You are right to be cautious - IRC is good for some things, bad for others. It is a good choice for a technical project community, and a very bad choice for discussion of politics.
You should assume the default for all IRC channels is permanent, publicly accessible logs. Very useful for
For a server such as freenode, here's a pretty standard setup:
- connect once to the server using your real IP
- register your nick with the server
- reply to the email they sent to confirm registration
- setup SASL on your IRC client
- disconnect and turn your VPN on
- connect back in, hope SASL works, then join a channel
This solves the I.P. problem. It will simply instead say "username joined from 111.222.333.444@Your_VPN, which leaks far less information. That protects you from rando's, but admins can still get you.
If you want to talk about something that's not a technical reference project, you'll probably want something else. I've heard Riot, Telegram, and Signal mentioned, but I don't know enough to recommend one.