Yes, Redmi Note 6 Pro does have the OTG support.
Redmi Note 6 Pro comes with Android 8.1 Oreo version. However, it is expected that soon, the latest version of Android will be available via OTA update.
Yes, Redmi Note 6 Pro does have the face unlock function as well.
Yes, Redmi Note 6 Pro does have the IR remote sensor.
No. Redmi Note 6 Pro does not have the front camera LED flash but it's display works as a flash.
The Redmi Note 6 Pro has it all - great display, snappy performance, no-nonsense features, excellent battery life, and very good and hassle-free camera experience. And all this is available at an amazingly low price.