Here is my drawing of Dark C3PO.
This is the time he turned to the dark Force of the Sith that was programmed into his system by Anakin.
These are my step by step process drawings ...
WOOPS . Too frowny
Eyeball dots better.
Original Image Drawing Reference Source: https://www.syfy.com/syfywire/mark-hamill-thank-you-anthony-daniels-rise-of-skywalker