To my understand, no drugs or treatments will change lp(a). They can only treat what lp(a) can affect which is of "...increasing risk of heart attack, stroke, aortic stenosis and peripheral artery disease" (https://www.heart.org/en/health-topics/cholesterol/genetic-conditions/lipoprotein-a-risks) . So the statin is to help reduce the other issues like cholesterol or blood pressure etc that co-factors that increase risk.

Short: No treatment for Lp(a), only can treat other potential factors that compound Lp(a) risks