The only reason why I do an upper lip lift specifically, my 3-D upper lip lift, is to shorten the distance between the nose and the upper lip. The other benefits of the upper lip lift are all fringe benefits, such as added upper tooth show, roll out of the vermilion, etc. If your upper lip is...
It actually has a lot to do with genetics. You could have your lower lip trimmed down some. However, the lower lip should be larger than the upper lip. Please don/t make it too small, or it will look odd.