How can I get this "Dark room corners" effect on my 3D map?

Hello and thanks in advance for reading!

I know it's probably a very basic thing, but since I don't know the right name for this lighting effect I just can't figure it out.

Here's what I'd like to achieve:

My guess is you have to use baked lights, but since I have a big interior map...does that mean I'm gonna have to place tons of point lights everywhere?

Thanks again for the help!

 

can do realtime,
https://docs.unity3d.com/Manual/PostProcessing-AmbientOcclusion.html

or baked
https://docs.unity3d.com/Manual/LightingBakedAmbientOcclusion.html

or could use vertex colors in the meshes also to make certain parts darker.

 

Thank you! I did try the ambient occlusion option in post-processing profiles, but it doesn't seem to work on any of the objects. Does it work regardless of the material shaders used?

 

and requires camera depth texture, but if its some default materials and shaders, probably that should be there..