ESP32 - Can I safely use GPIO ADC2 pins for non-adc use while using WiFi
Yes they are still available to the other function of the pins, they just can't be internally connected to the ADC2 module and used for analog to digital conversions.  

The Wifi usage of ADC2 is done internally on the chip and is not routed through the pins.

Some official development board do use some of these specific pins for other purposes (like auto programming circuits, etc) so may be unavailable for other reasons.