iOS 11.3 introduces new features such as settings for power management control—the feature that scales back performance on iPhones with degrading batteries to avoid unexpected system crashes. It also adds Business Chat to Messages, introduces Health Records for a unified view of all your medical records, ARKit 1.5, and four new Animoji characters.
It also changes HomeKit so device makers can add support through software updates instead of designing new products with HomeKit-compatible chips. In addition, it adds streaming music videos to Apple Music, and more.
iOS 11.3 developer beta 3 requires an Apple developer account. You can sign up at Apple’s developer website, or you can hold off for a couple days and wait for the public beta update.