In Korea and my ETS date is one year and a day after my DEROS. Will I PCS and ETS back in the states ?

Yes you only need to have six months to your ETS from your report date when returning from a dependent restricted tour

You can ETS in Korea, all you have to do is extend by submitting a FSTE (Foreign Service Tour Extension) packet to your battalion S1.

I'm certain you'll get the detailed answer with regard to any requirement to if it's done differently now, but..
there used to be US Army Separation Transfer Points. I served in one at Ft Jackson 82-85.
Soldiers separating (ETS, chapter...), would be flown from Germany and Panama, normally arriving late at night. They would be put up in barracks, and outprocessed the next day (DD214, final pay, orders, transfer/enlistment to ARNG/USAR/IRR, flights home). Reason was an agreement with host Nations, and to save money in lieu of PCSing someone solely to separate them.