I am almost certain that Sanji’s CoC will bloom once he realizes that his desire to protect and save people is one of the qualities of a King.
If we look at Sanji’s journey, it is always about him saving someone. The need to protect is ingrained in his spirit and lies at the core of his true potential.
There is a stark contrast here:
We have Judge, who sacrificed his own men as shields to win battles.
Sanji, conversely, is the exact opposite: he acts as the shield to protect his own and win battles.
The most innate and unique quality of a true King is not the desire to dominate, but the capacity to be the pillar that upholds and protects his people. A king who steps into the face of danger to save others possesses a far more unshakeable will than someone who fights merely for power while sacrificing their soldiers.
Sanji needs to "unlock" this realization—to understand that this is a noble ability, the mark of a true conqueror. He must accept his own power and channel it into his kicks so that he is always capable of protecting those around him.
It is deeply poetic to think that his power will not stem from the pursuit of a throne of King, but from his kind heart’s unwavering vow to always be there to protect everyone.