There's no doubt that levels can help 'expand' space, and a tall coop is great for ventilation up high...but....in a small foot print(4xX) getting up and down from those levels becomes a significant issue.
Expanding your coop size, or adding a covered run, will definitely be worth the time, effort, and money/materials.
Expanding your coop size, or adding a covered run, will definitely be worth the time, effort, and money/materials.