The entire church agreed to papal supremacy with the Formula of Hormisdas in 519 AD:
“Following, as we have said before, the Apostolic See in all things and proclaiming all its decisions, we endorse and approve all the letters which Pope St Leo wrote concerning the Christian religion. And so I hope I may deserve to be associated with you in the one communion which the Apostolic See proclaims, in which the whole, true, and perfect security of the Christian religion resides. I promise that from now on those who are separated from the communion of the Catholic Church, that is, who are not in agreement with the Apostolic See, will not have their names read during the sacred mysteries. But if I attempt even the least deviation from my profession, I admit that, according to my own declaration, I am an accomplice to those whom I have condemned. I have signed this, my profession, with my own hand, and I have directed it to you, Hormisdas, the holy and venerable pope of Rome.”
byzcath.org/forums/ubbthreads.php/topics/122063/The%20Formula%20of%20Pope%20St%20Hormisd
The phrase “first among equals” does not appear in any writing in the first millennium in reference to the Pope. It’s something Eastern Orthodox apologists made up in the second millennium.