Set procedurally generated objects as static

I am working on a mobile game in w$$anonymous$$ch levels are procedurally generated. Now I have come to a point where I can spawn trees and rocks etc randomly. I need to declare those objects as static so I use t$$anonymous$$s code-

GameObject g=Instantiate(prefab, position, rotation); g.isStatic=true;

https://docs.unity3d.com/Manual/StaticObjects.html T$$anonymous$$s documentation says that setting isStatic at runtime has no effect.

So is there any way to generate the world before actually loading the runtime scene so that static property would work?