The International Space Station weighs about 420 tons and took about fifty space shuttle launches to build. The Starship upper stage has more volume than the International Space Station. A larger, stretched Starship upper stage could be built and launched to enable larger space stations by just leaving Starships in orbit.
An older SpaceX design was the Interplanetary Transport System. This older design was larger than the Starship Superheavy. ITS would outperform the Saturn V by a factor of 4.1 on the mass delivered to Low Earth Orbit. In a fully expendable configuration, ITS would loft a LEO payload of 550 metric tons while the reusable booster can send 300 metric tons into orbit. The improving Raptor engines are getting to 60% of the proposed ITS capability.
If SpaceX achieved a further 20% improvement in the Raptor engines could enable about 360 tons in expendable mode and 216 tons in reusable mode.