Try the beta…
>>> public beta versions of iOS 11, macOS High Sierra, and, for the first time, tvOS should be available by the time you read this.
Sign up to participate in the public beta at beta.apple.com. If you choose to test out any of these beta versions, remember that you could encounter some issues, so make sure you back up your data. Also, for High Sierra, it’s wise to put it on a separate drive away from your existing installation.
Bear in mind that the public beta software is confidential. By signing up to access it, you agree not to disclose details, publish screenshots, or share the software with other people who aren’t also in the public beta program. Only details publicly disclosed by Apple itself are considered to be no longer confidential.
You should find an app installed as part of the beta versions that enables you to provide feedback on any bugs you discover, or to suggest changes to the software.
Installing a public beta version does not void your hardware warranty. However, bear in mind that it’s best to install on a device that isn’t your main one, if possible.
You can restore your Mac or iOS device to non-beta software by following Apple’s instructions at bit.ly/betarstr. Before installing any of Apple’s operating system betas, read its Frequently Asked Questions at bit.ly/applbetafaq.