It's popular opinion expressed here that single family zoning is the only thing limiting supply. I'm not sure it's correct. There's a limited amount of construction capacity in every given area. Limited amount of construction labor (construction workers, engineers, managers), construction equipment and materials. It's not easy to scale it up. Upzoning is not a panacea.

Then normal market forces take over - as demand for extra construction equipment and materials increases, people realise they can make money there, so supply increases. It takes time and certainty, but there's nothing inherently stopping people building more cranes or training more electricians.