There are currently 300 employees. This manufacturing rate will be comparable to the speed of construction of commercial wide-body airplanes.
Elon has said that mass production will bring the cost of the Starship down to $5 million. There will be six Raptor engines. This means the mass production of Raptor engines at less than $1 million per engine.
Larger buildings are being built in Boca Chica to shelter the construction. There will need to be a lot more buildings and a lot more heavy equipment to speed construction.
There will need to be more factories to build the Raptor engine and the conversion of the existing Merlin rocket engine factory to Raptor engines.
Elon Musk has the Tesla experience where he successfully built factories and scaled mass production.
The Starship will be reusable hypersonic vehicles. The Starship can fly at mach 15 to mach 26. The Super Heavy Starship will be more expensive but heavier payload capacity hypersonic vehicles.