Setting D+ D- ports to set 12V From Qualcomm QC Chargers
Tried on mi 20000mAh powerbank.
It works, but you need to do this before using the table to set appropriate D+ and D- to adjust voltage output.

According the description in the CHY100 datasheet, the processes to enter QC2.0 are:
2.2 E-fuse and Interface
− − −
Apply a voltage between 0.325 V and 2 V to D+ for at least 1.25 seconds
Discharge the D- voltage below 0.325 V for at least 1ms while keep the D+ voltage above 0.325 V Apply the voltage levels in Table 3 to set the output voltage. (must keep the D+ voltage above 0.325 V)