During my learning process i have actually successfully been able to make some simple working ermmm things. 
But most if them are done using many different premade assets.
I’ve noticed the buildsize is sometimes 100mb on windows, 40mb on mac, and 14mb on android.
I understand you can change the quality etc in the project settings menu…
But here is my question!
Do unity include “everything” in my project in my builds, or does it only include the actual items used?
I know i have both extra C# scripts from experiments, random textures, random models from blender testing.
If (Are all those "unused" assets included in the build){
is it possible to automatically "not include those in a build?";
}
Thank you in advance.
Vaupell