Katakuri and Ace have it, but I understand what he means.
People with Coc are incredibly charismatic, they draw people to them with their mere presence. They have that certain something. Zoro impresses others by performing amazing feats, but he's average when it comes to charisma.
That those super charismatic people are also often leaders seems like a natural consequence, but not a given if the one he/she is working for is even more impressive.
But who knows, maybe Oda will break the pattern and give it to Zoro anyway. Maybe Zoro himself changes over the course of the next months (manga time). Obama wasn't always the guy we know today.
I'd say being charismatic is just one aspect of it. As with many things, it all comes down to force of will and the many means by which it can be expressed and hold sway over others. A better word – although it arguably all comes down to semantics -- would be 'influence" when breaking down the power of CoC. And as we've witnessed many times throughout, there's more than one way to "conquer" multitudes: beauty, cooking, compassion, music etc....with many more instances to come, I'm sure.
So yeah, I myself am expecting ALL of the Strawhats to reveal CoC -- whatever the form it may take -- by EoS at least.