Shrink and grow entire assets from the asset store?

Hello guys I have a question. I just imported a whole city asset from the store, and I imported an apartment asset from the store. I want the apartment in the city. When I imported the apartment it was actually bigger than the city, so I couldn't put it inside. I tried to shrink the apartment, but each lamp and floor tile and door was a seperate 3d model, so it shrunk each thing individually and long story short it didnt work (ill put a screenshot to show cuz i cant explain tbh). I then tried to grow the city, but each building was separate and that didnt work either.

I need to know 1. how to shrink entire assets at the same time together or 2.how to combine unity 3d models into one big 3d model (so i can shrink and grow everything together)

apartment before i tried to shrink it


apartment after i held right click, highlighted everything, and used the scale tool to shrink everything

 

Select Structure_02 in the hierarchy, then set to Scale instead of 1 to 0.5, verify that this proportionally reduced the building by half. You don't have to make everything smaller, just make the main object smaller.