While he did indeed become a cardinal
at 13, Giovanni de Medici
actually was unable to make use of the privileges
of his office until he turned 16.
Furthermore, although corruption, nepotism, and venality flourished in the Catholic Church under his reign, Leo X was an important patron. He funded artists such as Raphael, as well as poets and scientists. He did, however, manage to live in such opulence as to empty the Vatican's coffers in only two years.
He died in 1521 at the age of 45.