Yes, Oppo F9 does have the double channel LPDDR4X type of RAM.
Oppo F9 has ARM-Mali G72 MP3 GPU. The peak frequency of the GPU is 800 MHz.
No. Oppo F9 does not have the IR sensor.
Yes, Oppo F9 does have the GPS support.
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.