A commentor here observed that the Merchant and Empire books are set in a small world. It’s an interesting observation, and one that deserves some thought, because a lot of fantasy and sci-fi books seem to sprawl. They cover an epic-worth of territory, sometimes by design, sometimes just because it seems traditional.
But not all stories need sprawling worlds. Some books, even novels or series, fit better in a small space, a human or other person sized space. Which is sometimes difficult to do.
To me, it seems that one key lies in the details. Not loading the story with so many descriptions and details that the plot vanishes into the setting (although there are places and times to do just that), but careful description so that the reader gets a strong sense of where the world extends to and where it ends. What is the protagonist seeing, hearing, smelling (or not smelling), tasting? Keep it within line of sight and scent, and the reader will come to think of the character’s environment as small and somewhat constrained.
Limited points of view are also very important. Third person omniscient works great for some things, as does first. First person is the most limiting PoV, and for me the hardest to write. I find third person limited (past) works much more easily, especially since I often write male protagonists. Limited third keeps the reader close to the character’s own limits, but allows some distance. It’s not as “crowded” as being inside someone’s head. I also prefer past tense, in part because it lets me use slightly archaic or specialized language more smoothly. Since the reader only sees or knows what the protagonist (or PoV character) sees and knows, the world tends to stay small.
What are the PoV character’s goals? Taking over their world? OK, harder to keep in a small sphere. Getting something done and then going home at the end of the day? That’s a bit more limited. Traveling on a business trip that is limited to animal speed, not losing money or falling ill or getting killed, then coming home to a small city and a family there? That’s a small and realistic goal.
I think of the Merchant books as “blue-collar fantasy.” Before you point out that Tycho and his son would be considered white-collar today, think about what they have to do in addition to just buying and selling. They handle livestock. They load and unload their own goods, with mechanical aid if possible. They help do the grunt-work on ships so that the sailors can focus on other things. They oversee quality checking animal hides, which involves learning the basics of tanning, and livestock husbandry. They walk everywhere they can’t sail. Other characters are a stone-cutter and his partner, and their apprentice. They work in mines if they have no choice. The upcoming book features a widowed salt worker. He loads and unloads and chops firewood, deals with boiling brine and salt, and other equally fun, easy activities. He’s also part of the city militia, since he is a citizen of the city. But the salt workers are second class, or would be if they hadn’t threatened to tear the place down several decades before when the abuse got too bad.
No princes, no dragons, nothing really mythical. Yes, the gods are active in the world, but they are also somewhat limited, and don’t always agree on what to do. It’s a limited setting, with characters who are very pragmatic. They don’t want to run things – that’s what the Great Northern Emperor’s job is. They want to keep a roof over their family’s heads, food on the table, and to live as comfortably as their incomes allow.
It’s not a good setting for a lot of things, but it works. There are stories that need huge, sprawling worlds. Ender’s Game wouldn’t work in a small setting, although at least at first, the novel does have a constrained feeling to it. The Dragonriders books are large. But the Harper Hall sub-trilogy is smaller, especially most of the first book.