This was one of my introductions to military history. I was 14 and haven't ever really looked back. Big fan of star forts and Vauban.
Star forts like this were constructed after gunpowder became common in warfare! The elevated position plus the angled walls were designed to make it harder to just blow a hole in the wall with a big cannon, which is what happened to a lot of pre-gunpowder fortifications.
Excessively elaborate plan, easier to just pillage the countryside and then camp out for several weeks just outside of firing range and prevent food deliveries from coming in until they run out and begin to starve. If they've got aqueducts you can fuck those up to speed up the process. If you can poison their cisterns that's also good.
Camping out is maybe a lil more expensive than whatever this guy's doing because you've got to feed YOUR troops the whole time but you can't beat it for effortless style.
Another good method is to just get the town's billionaire-equivalents to come out and talk to you, whereupon you say "Hey what if instead of killing everyone here, we just take over and make you a client state, then YOU PERSONALLY can make more money :)" but you need some infrastructure to back this, like trade networks and some Empire clout so they start considering the merits of a "If you can't beat 'em, join 'em" approach
but [sarcastic jazz hands] everyone just wants to blow holes in a perfectly good wall because that's more fun
