Yes, Oppo F9 does have the double channel LPDDR4X type of RAM.
Yes, Oppo F9 is a dual VoLTE mobile phone. You can use 2 4G network sim cards at the same time.
Oppo F9 has ARM-Mali G72 MP3 GPU. The peak frequency of the GPU is 800 MHz.
Yes, Oppo F9 does have the face unlock.
The most striking feature of the Oppo F9 is the big display with the waterdrop notch. It is well designed, delivers good battery life, and offers decent performance for the price.