Most of the phones can use High res API via USB Dac. The High res output that we are talking here is with internal DAC of the phone. While your phone might have internal DAC, OEM's decided to disable it in the software level and max can't add high res audio path to ROMs.
Attachine the high res menu on a compatible device for example (OnePlus 3T). I'm not using AUX because this is still broken on nougat for the current alpha version so i'm using my B&O DAC that came with the G5.
EDIT: After digging abit on the internet, I don't think that your phone have High res capable ha