The first time you bake cookies you don’t make 768 cookies.
You may ultimately intend to have 768 cookies but generally you still bake them a few at a time, perhaps 12 at most or so, until you understand what is involved.
Otherwise you might mix 768 cookies, put them all in a massive oven, and burn them to a crisp because you misread the temperature.
This is called iteration. You are engineering a game. Iterate steadily towards success. The first version of your game should have one level. Then when that plays “good enough,” try putting in another level.
And as @Moonjump_1 correctly points out, you might realize “hey, both level 1 and 2 have the same light and floor! Why define it twice!”
Now is where Unity shines. Additive scene loading is one possible solution to help you organize:
A multi-scene loader thingy:
My typical Scene Loader:
Other notes on additive scene loading:
Timing of scene loading:
Also, if something exists only in one scene, DO NOT MAKE A PREFAB out of it. It’s a waste of time and needlessly splits your work between two files, the prefab and the scene, leading to many possible errors and edge cases.