We know that before the official announcement of its next Android version, Google likes to roll out a few developer previews a few months before the launch. Android P will be officially announced in Q3 2018, and a total five developer previews will be made available in this period. Here is how Google mentions all the developer previews on its official website –
Preview 1 (initial release, alpha)
Preview 2 (incremental update, beta)
Preview 3 (final APIs and official SDK, Play publishing, beta)
In the past, we have seen Sony rolling out the Android N Developer Preview for the Xperia Z3, and recently, Xiaomi announced that its Mi Mix 2S is getting the Android P Developer Preview soon (as early as May 8th tentatively). The Xiaomi Mi Mix 2S will get all the new features that are present in Android P. This was announced on the official forum, but the post is now taken down. You can check it out here.
Since the post is now taken down, you might think that this is not going to happen. But, the folks at FunkyHuawei were able to get the official OTA of the Android P Developer Preview for Xiaomi Mi Mix 2S that confirms the fact that Xiaomi is indeed working on it.
Finally, it would be better to wait for the official update to come to your Xiaomi Mi Mix 2S as these leaked builds might break some things. There are chances that your phone will go into boot loop so try it at your own risk.