Xiaomi has released the first MIUI 12 update for the Redmi K30 Pro and Poco F2 Pro. The update has been distributed to the EU branch of MIUI, which is different to the global one. We would recommend checking which branch of MIUI your device is on before trying to upgrade. You can do so by heading to "About Phone" on your device and looking for its MIUI version. If it contains "EU" in the build number, then your device has been enrolled on the EU branch of MIUI. By contrast, global editions have "MI" in their build numbers.
The update for the Redmi K30 Pro and Poco F2 Pro is called V12.0.1.0.QJKEUXM. It has already started hitting some handsets as an over-the-air (OTA) download, but you can install the update manually. The OTA is 1.1 GB, while the full ROM is 2.8 GB. Both can be downloaded from the corresponding hyperlinks, which point to files hosted on Xiaomi's servers.
There has also been multiple reports on Mi Community of people being unable to upgrade their Redmi K20 or Mi 9T to MIUI 12. The concerns have seemingly been raised about global and EU versions of the devices and not the Chinese branch to which MIUI 12 has also supposedly been released.
Confusingly Xiaomi's feedback team simultaneously states that the update has and has not been rolled out to devices. On one thread, the feedback team states that the update is being pushed out in batches, which may explain why some people remain on MIUI 11. However, in another thread the feedback team claims that MIUI 12 for the global version of the Mi 9T remains in beta. It seems that some people have been unable to install the update manually too, which suggests that MIUI 12 remains in beta for some Redmi K20 and Mi 9T handsets. Xiaomi is yet to make an official statement on the matter, though.