"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Apple Seeds Second Beta of iOS 11.4.1 to Public Beta Testers
Beta testers who are members of Apple's beta testing program will receive the iOS 11.4.1 beta update over-the-air after installing the proper certificate on an iOS device.
Those who want to join the beta testing program can sign up on Apple's beta testing website, which gives users access to iOS, macOS, and tvOS betas. iOS betas are not always stable and should not be installed on a primary device.
There were no notable features discovered in iOS 11.4.1 in the first two developer betas, suggesting it focuses on bug fixes and other minor improvements.
iOS 11.4.1 will be one of the final updates to the iOS 11 operating system now that Apple is shifting its focus to iOS 12.