https://wccftech.com/ios-11-2-will-enable-7-5-watts-fast-wireless-charging-on-iphone-x-iphone-8-iphone-8-plus/

In case you were wondering which version of iOS will enable 7.5 watts of fast wireless charging on iPhone 8 ,iPhone 8 Plus or iPhone X, now you know.

With the announcement of iPhone 8, iPhone 8 Plus and iPhone X, Apple also revealed that its new smartphones support the Qi Wireless charging standard. This means that you can go ahead and pick one of the many compatible charging mats out there to make use of this wireless technology. However, Apple also revealed that its smartphone lineup will support up to 7.5-watts of fast wireless charging too. But unfortunately, that is something not available for everyone out of the box.