Will a winged scapula lead to scoliosis?

Not usually. A true winged scapula is related to an abnormal function of the muscles that anchor the scapula to the torso and is usually nerve related. It in of and of itself is not usually related to scoliosis. But, the first changes of scoliosis is a rotation of the vertebrae which causes a rib hump, also known as an asymmetric trunk rotation. This may make the scapula appear winged. Thank you.
Possible . There are scoliosis types that develop as a result of neurologic issues and a winged scapula may be a sign of this or it may appear to be winged due to the rotational component of a typical scoliosis which is not just a curve but a coiling of the spine just like twisting a rope into a coil or spiral.
Not by itself. However, whatever muscle weakness caused it, is likely to pull on the spine asymmetrically, and contribute to scoliosis.