Paul was leader of the apostles he was never explicitly appointed head of a church.
This begins its development as Church structure at the level of deacons (diakonoi), priests (presbyteroi), and bishops (episcopoi) as you can see right in the pages of the New Testament, as these offices are passed on by the laying on of hands, to replacements and successors (Matthias, Timothy, Titus, etc.)
This authority derives from Jesus giving the keys (the symbol of authority), the power to "loose and to bind," to His Apostles; and His declaration that "whoever hears you, hears Me."
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