How to improve lighting in big scenes?

I have a problem improving the lighting quality on my latest scene, my scene has this huge building in it and no interiors, so I wanted to improve the lighting quality using the baking option but the lightmap texture resolution had to be increased to make it look good, but it consumes up to 20GB of RAM and it crashes.

is there a way to improve the lighting quality of a scene as big as this or how could I bake a scene as big as this?

Hi!

You should break up your scene into levels… Look into level streaming!

Hi! I saw that in level streaming you should divide your assets carefully because there can’t be shadows from one level to another, so, in a scene like this where everything is connected, how would you do it?