How does Civilization IV rapidly expand urban coverage by occupying cities?

Culture determines the boundaries of your city, building libraries, temples, arenas, theaters, etc. Improve your culture in occupied areas, or expand a city on a large scale with great artists. However, when a large-scale war breaks out, I still suggest that you raze all enemy cities to the ground. If you want resources, emigrate and rebuild the city yourself, so that it is easier to manage the city, so that your army is not bound, reducing the pressure of repression and the troops needed for garrison. Look at how Mao Zedong dragged the Kuomintang to death, gave a bunch of empty cities to his opponents, and let powerful opponents gradually reduce their mobility, and finally broke them one by one. Kind of like playing with civilization. Of course, computers don't have this kind of trouble. They cheat openly.