Recently, Asus released an Android 10 beta for the ZenFone 5z. Now, the phone has a stable build that will be rolled out to users in general. This update adds a dark theme and a more streamlined UI to the 2018 flagship.
https://www.notebookcheck.net/The-Asus-ZenFone-5z-officially-gets-upgraded-to-Android-10.444951.0.html