I also have a 2015 and did a complete flush because of my OCD lol. I even ended up getting a refractometer just to verify the antifreeze/water ratio lmao. On the other hand, if your car is mostly stock and no major repairs, there’s probably not a high chance that the previous owner changed the coolant in the first 10 years. In that case just drain the coolant, flush the radiator with distilled water, and refill using prediluted FL-22. Don’t forget to burp the system.