ISTANBUL — Fighter jets raced across the Istanbul sky, painting the Turkish flag with ribbons of colored smoke, as a military band with nearly 600 musicians marched below. Hundreds of thousands of people looked on, in an event that quickly took on the fervor of a religiously infused political rally.

The event being celebrated so lavishly last Saturday occurred 562 years ago, when the Ottomans conquered what was then called Constantinople. But its themes of conquest, piety and Ottoman nostalgia made the celebration a powerful metaphor, highlighting the triumphs and ambitions of one man: President Recep Tayyip Erdogan of Turkey.

Never mind that when Turkish voters choose a new Parliament on Sunday, Mr. Erdogan will not be on the ballot. The election will still largely be a referendum on him, and on his plans to transform Turkey’s Constitution and concentrate more power in an executive presidency. A big victory would also represent a new milestone in Mr. Erdogan’s drive to eclipse Mustafa Kemal Ataturk, the founder of modern Turkey, in the history books as the country’s pre-eminent figure.

To many of his supporters, Mr. Erdogan already has.

“I really just came here to show my support for Erdogan, my tall man,” said Fatma Sahin, 32, as she waved a white Erdogan flag at the rally. “He doesn’t just deserve the presidency, he deserves to be king.”