Are ambercrombie shirts opposed to be loose or tight?

i'm 5'6 and weigh about in my early hundreds i am not sure i brought a lx from ambercrombie kids and it was so loose on me and it wasn't fitted at all like it says muscle fit then i brought a large it fits ok but it still is loose... is this normal for ambercrombie kids shirts to be loose around the sides? and a l and lx doesn't stick to my chest?