IRC is a standardized protocol. The best resource for learning about the IRC protocol is ircdocs.horse, which essentially tracks the IRC living standard. Many libraries are available for various programming languages to make IRC bots easier to write, finding one for your language is an exercise left to the reader. In any case, writing an IRC client implementation from scratch is very easy.
Do not bring your IRC bot into a channel without permission from the channel operators.
You can find various IRC-related software projects implemented by sourcehut users on the project hub.