If you have the "threadless" stem the top cap screw does not move the bars. If it s quill stem the screw adjusts a wedge at the bottom of the stem which can be used to adjust the stem height, but it is not as simple as turning the screw and the bars move. Here is an article you can read and see what is involved. Hands Up (Or Down)! Adjusting Handlebar Stem Height on Your Bicycle

Edit: Some bikes are equipped with an adjustable stem, where you can change the stem angle.