Question about Baking before/after array modifier


I have a quick question i couldnt find any answer to.

Im still a super blender noob, so I might miss some essential work arround stuff…

I want to modell a stairway simple to the well known pic of stairway to heaven.

Important is to bake of it a normal map and the albido/diffuse in one image with the applied array modifier.

Im using the “selected to active method”.

What would be the way to get the applied low poly/detail modell so I can bake it?