Yes, Oppo F9 does have the MicroSD card slot. You can expand memory up to 256GB.
Yes, Oppo F9 is a dual VoLTE mobile phone. You can use 2 4G network sim cards at the same time.
Yes, Oppo F9 does have the OTG support.
No. Oppo F9 does not have the IR sensor.
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.