As a general statement, changes in the septum can change the external appearance of the nose. Since the septum is very involved in the projection and rotation of the tip, septal surgery alone does have some influence on how the nose looks. A nose may look crooked because of a crooked septum or it may not be related at all. How much it will effect your nose depends on many factors: your anatomy-both the size and shape of your nose and how much the septum is involved with tip support, what your surgeon ends up doing to your septum has a big influence as well. It is possible to do a minimal elevation septoplasty and not change the outside of the nose at all while it is also possible to do an extensive septoplasty and change the septum's relationship to the rest of the nose. This is pretty confusing but the bottom line is you need to put these questions to the doctor performing your surgery.
I hope this was helpful.