Qi Charging transmitter types
Apple decided to deviate from QI standards. 7.5W is not a normal QI rate, and you cannot get 7.5W charging without apple specific protocol. Apple devices will work at the 5W rate.
https://www.zdnet.com/article/iphone-and-android-wireless-charger-pads-which-one-is-the-best/
Samsung also did the same for their high speed charging. WPC/QI charging is limited to 5W. You need Samsung fast wireless charging v1 or v2. https://www.samsung.com/global/galaxy/what-is/fast-wireless-charging/
So your P9242-R QI 1.2 design can do 15W, but Apple and Samsung both don't care about that.