Yes and No.
The nasal septum is a midline structure in the nose composed of cartilage and bones. It is the main structural support of the nose. Without a good septum, breathing function is compromised.
There are some parts of the septum that are visible (top and front parts), whereas the other parts of the septum are not visible (inside part). Depending on where the deviation of the septum is located , it may or may not be visible.
Deviations involving the top or front parts of the septum can cause the nose to appear visibly deviated, while deviations involving the deeper portions of the septum will not cause any visible deformities.
Correcting the deviations in the top and front parts of the septum will change the appearance (straightening a crooked nose) even if the goal was purely to address breathing issues.
On the other hand, if your deviation is not involved in the top and front septum, it will not change the appearance -- unless you want to, in which case the surgeon will use the excess cartilage obtained from the correction (very precious and excellent material for augmentation that would be otherwise thrown away) to create the changes you want.
