Netflix supports High Dynamic Range (HDR) video on the new Apple TV 4K, the iPhone 8, iPhone 8 Plus, iPhone X, and likely Apple's latest generation iPads as well.
What's New in Version 9.37.0
● Support for iOS 11
● HDR video (on supported devices, Premium Plan required)
You can download Netflix from the App Store for free. More details on its support for HDR can be found here.