It's very obvious that the photo is work of professional photographer with assistance of another professional stylist or photographer.
The creators skillfully placed half-opened backpack on the left side so that it leads the viewer's eye to the hand of the girl with which she signals to the assistant holding the reflector to position it slightly higher.
Compositionally, the main part of the scene is arranged in the shape of a large triangle that contains additional sub-triangles, namely both arms; one arm and the head with falling hair; and the legs clad in deep blue jeans, one of them showcasing a new shoe. Even the face of the baby and its hood resemble two triangles. Finally, by using a wide angle lens, the photographer masterfully added the alley itself as another triangle in the background.
It's regrettable that the photographer overlooked the potential to arrange also the backpack into a triangle shape. Closing it on the top or squeezing gently the opened flaps would have done the trick. Otherwise, it is a great composition with a lot of fine geometry. Clearly, a lot of preparation, professional expertise, thought, and planning had been put into the creation of this image.