As first spotted by The Verge, Apple has quietly updated its support page to reflect the change:
Additionally, users can see if the performance management feature that dynamically manages maximum performance to prevent unexpected shutdowns is on and can choose to turn it off ... This feature applies to iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE, iPhone 7, and iPhone 7 Plus. Starting with iOS 12.1, iPhone 8, iPhone 8 Plus, and iPhone X include this feature, but performance management may be less noticeable due to their more advanced hardware and software design.
As part of the fallout from Batterygate, Apple introduced a cheaper battery replacement program through to December 2018. But as Apple notes above, the newer models probably won't be as crippled by "performance management" due to their upgraded insides. Regardless, batteries inevitably age, but at least you can keep an eye on your battery health via the settings -- where you can also disable the throttling function if you so wish.