He already unlocked the potential for it, IMO. CoC is the ability to look death in the face and not back down.
Roger showed it by dying with a smile on his face as he created the new era
Shanks had it at the start of the series when the gun was pointed at his head
Zoro unlocked it by taking Mihawk's final attack head on
Luffy unlocked it by smiling at the execution stand
Jinbei unlocked it by standing up to Big Mom
Yamato unlocked it by challenging her father over and over again
Koby unlocked it at Marineford when he stood up to Akainu.
Nami just unlocked it by denying Ulti, and then verbally challenging Kaido:
That's why few have CoC: you have to look death in the face and survive with nerves of steel.
Usopp will unlock it on Elbaf, IMO. No IDEA what the hell Oda is doing with Sanji, though.