Could cocaine make your nostrils bigger?

Not that I know of: but what it can do is cause the nasal septum, the piece of cartilage that separates the left and right nostrils, to deteriorate, ultimately develop a hole and potentially collapse, causing the nose to flatten. It can cause nosebleeds and sinus infections, as well as all the systemic problems - heart attack, stroke, paranoia, aggression, depression etc. If this is you, get help with stopping now.