So I have three ideas
So in every map I have played there was always a body of water nearby at the edge of the map and I was thinking maybe late game after you have access to the town building designs you are able to build a dock and depending on the size you make it you can have larger and more boats. And these boats will let you fish, trade and attack other settlements (see later on).
Bigger Maps and other cities:
So I was thinking that we could have bigger maps over all, what this would let other towns and settlements be able to exist far away, Some could be sprawling cities when you start and others can start after you so they are not all the same size. And these other settlements / cities would act like city states, where they would form trade agreements, alliances, and declare war on each other. And say if the cities are farther away it would take longer for the news to reach your settlement. And in the beginning of the game you can decide if you want to join a major faction, make your own, or be a pirate city that would always attack other cities. Each with their own benefits and draw backs. Like if you join a major faction, you make more money and can make better trade deals with the nation, but you cant declare war on some other cities. While if you went independent you can trade with who ever and declare war on who ever but you don’t get as good trade opinions with major factions. And if you went pirate or outlaw settlement, you can trade with only other pirate/ outlaw settlements and you are attacked on site.
So say you attacked another settlement and instead of killing everyone up rite you can capture their people who surrender and try to convert them to your own settlement. But as a draw back they might leave your settlement or try to start trouble.