it was determined that my gas cap is leaking so my question is, if I changed the cap out myself does the code clear on it's own or does the dealership need to do anything?

Be aware some aftermarket gas caps do not seal properly and the same problem will continue. I have experienced this at the shop on various makes and models - but not on a Kia. Just a word of caution.. The code can be erased using a code reader - that I’m sure someone you know has.. It will eventually go away by default if problem actually has been resolved. Good luck!