Is it permissible to continue supplicating for increased height after growth has ceased at the age of 20, while taking the necessary means, practicing sports, and performing Qiyam al-Layl out of humility to Allah the Almighty?

Making supplications for increasing height after the growth phase is impermissible, and it is considered an transgression in supplication because it is asking for something that is usually impossible. Transgression in supplication occurs by asking for what is impermissible to ask for, or for what Allah does not do, such as asking for immortality or for the removal of human necessities. One must be content with what Allah has apportioned and busy oneself with thanking Him for His blessings.