Just from my personal experience relating to banworthy things.

Make the rules clear and unambiguous and include the penalty for breach within the rule body itself.

And have an absolute heart of stone. When you ban somebody, you quote the rule, and you do not add any personal narrative. You ignore every appeal for decency or clemency. If somebody cannot be bothered to read and follow the rules, they have already forfeited the right to be a part of your community in any way. Do not allow yourself to be swayed.

Even if there is some ambiguity or sense of injustice, that's just too bad so sad. "Oh no, I don't get to post for 24 hours on some random forum about some bullshit that doesn't really matter". Wah. If they can't get over it, they weren't going to add anything useful to your community anyways.

If somebody sends you an appeal and you don't want to argue with them, simply don't argue with them. If they keep coming at you, making your life hard, or swearing at you, just keep extending the ban or make it perma.

We aren't dealing with bars of gold here, it's mostly random horseshit posted to communities that we talk about for a few days and then forget we even saw. I mean I loved the community that I built and nurtured for 14 years but really at the end of the day after I walked away from Reddit from the API changes, I haven't noticed one iota of difference in my life.