In my opinion, you shouldn't be too stress on "what to do" on your discord. Because ultimately what i think shape your server is the people in it, so there's no need to make something if people haven't ask of it yet.
But that's just me.
That being said, i'm making one myself, and i feel so hype making it lol, what i'm saying it it's not that bad to develop it even before anyone's there too.
So in that regard, i think what's best is to learn from others, join some discord that you like or love even, and see how they make stuffs.
Most servers first channel is probably the welcome/introduction/default/rules channel. Then next is probably chatting/discussion.
And the others probably depend.
Like game server have bug channel, while you don't have to have that at all.
I think it's also depend on what type of server/community you wish it to be, qidian/webnovel discord have "level-thingy" that i still not quite understand lol. But i think it encourage more people to chat. But at the same time some articles on "how to make good discord server" said to not do such thing because it could make people chat because they want the level and the privilege it come with, in short un-genuine chats.
I myself not sure, at first i thought of doing that but then i think i shouldn't since i myself won't like doing that because it's tiring. So i also think thinking of "what you want if you join your favorite comic discord server" is important, don't do what you yourself won't like doing if you're not the creator but simply a member
I think it's also a good idea to make poll channel or use the chat channel to ask your readers what would make it fun for them.
And there's also this thing called "role", it worth to find out to enhance your server.
Since i found people use lt even as notifications.
And the last thing i could think about discord server is probably name. It'd be fun if you spice it up with names from your comic.
An example, maybe naming the chat channel as "your character name's Room". So it's like, people chatting on that character of yours room XD How fun is that for a fan!
I apologize to not being able to explain more properly, i still hope it serve as something useful even if a little bit ;-;