The bot sends /join #channelname it’s then in that channel. So you need to figure out how/the best way for you to instruct your bot to do that
Correct. That is what I would build and have built.
Some people will use a web panel to allow people to login and add a bot.
Other people will let the bot be in the bots own channel, and casters can use !join to make the bot join their own channel.
I prefer the web panel approach since I have other bot controls in the same panel and need oauth permissions for various other things tied to the bot.
The bot at boot can load the channels to join from storage and away you go.
The bot will also need a way to be communciated with to join new channels without fully restarting the bot each time to add a new channel.