According to Apple Technician on the Apple Chat, Apple does not cover cosmetic wear. They only cover accidental damage (cracks and accidental damage). Off topic, in order to get AppleCare+, we have to officially buy a new iPhone from the Apple Store and we have 60 days of the purchase date to activate AppleCare+. With refurbished phones purchased from third-party websites over 60 days of the purchased date (not the date we bought the iPhone from the third-party websites), we cannot purchased AppleCare+ because the third-party sites purchased the phones on its release date and they sell the phones to buyers online. They do not purchase AppleCare+ for the buyers.
Apple Technician suggested me to schedule an appointment to go see a Genius Bar at the Apple Store to have it checked whether they can fix the cosmetic damage. Keep in mind, Apple does not cover cosmetic damage. Since I avoided that option, I would want to wait until an accidental damage of my phone happens.
It does cost $129 dollars without AppleCare+ for replacing a small oleophobic coating scratch on the screen. In the near future when you buy a new iPhone or any smartphone, buy a screen protector to protect your phone from numerous of scratches so that your keys or any sharp objects only scratch the screen protector.
I am also reading outside sources as well, they use Oleophobic Coating solution or Displex to get rid of the scratches on the iPhone. I never experimented those two, but I felt the Oleophobic Coating solution only cleans the phone and Displex repairs the scratches on the phone. However, Displex does not cover up the deep scratches. I had that phobic issue once with my previous iPhone 5 that my fingernails made a deep scratch on the oleophobic coating of the phone when I tried to remove the phone case off my phone. Every time, I have difficulties removing the screen protector or case, I end up getting a scratch. I found out when I tried to put on the screen protector, it turned out to be a deep scratch on my phone and I ended up with fingernail air bubble line on it.
I tried every home remedy solution according to online sources, but it still does not cover the deep scratch. I am still finding out a solution in how to cover these deep scratches without damaging the oleophobic coating of the phone and the phone itself.
I would suggest not to try sandpaper or alcohol because of its roughness and harsh chemical. This process will develop more deep scratches on the phone and it will completely damage and ruin the oleophobic coating.
Right now with my iPhone 6s, I have a minor fingernail oleophobic coating scratch on the left hand bottom edge of my iPhone after changing my screen protector. It was difficult for me to remove the screen protector on that phone and it was stuck on there very well. I am trying to resolve this minor scratch issue without going to the Apple Store to have it checked.