Pruning a tree to make it smaller (known also as “topping”), particularly a large growing tree, is ill-advised and should never be done except in a few cases where it is necessary to preserve the tree. Topping a tree causes an immediate serious injury by removing too much live growth, and creates long term health and structural problems. If a tree is in good structural condition, it should not need to be made smaller.
An exception is when a tree contains structural defects (splits, cavities, poor unions) that could be corrected by reducing the overall size of the crown. Done correctly, a “crown reduction” type of pruning could add years to the life of a valued tree.