How does amount of flour affect cookies?
A general answer, because a concise answer would need an entire recipe.

(all ratios that follow are by weight not volume measures)

Flour gives the cookie structure. The commonly followed ratio is:


  Cookie dough = 3 parts flour, 2 parts fat, 1 part sugar


That 3:2:1 ratio results in the most common cookie texture.

Adding more flour give you a hard cookie like: ginger snaps, short bread, etc.

Reducing the flour, like a 1:1:1  flour-fat-sugar will give a drop cookie and often chewy.

I Googled, and found this informative piece How to Invent a Cookie Recipe.