The highly-anticipated MIUI 12 update will make its way to Xiaomi and Redmi devices starting May 19th. A total of 32 devices will be eligible for the MIUI 12 open beta before the final release hits the airwaves. Users on the beta version of MIUI 11 will get the software via an OTA while those on a stable version will have to sideload it.
https://www.notebookcheck.net/MIUI-12-will-be-available-globally-starting-May-19th.464373.0.html