USB-C How to detect an Audio Accessory with Charge Through
this may help you:
A UFP is defined as having an Rd on its CC lines. If Rd is less than Ra (Ra = 1 kiloOhm ± 20 %), then the DFP would recognize this device as an audio accessory

Type-C receptacle &lt;-------&gt;   [TypeC-Plug &lt;=&gt; Audio 3.5mm]
CC1               &lt;-------&gt;   CC1 &lt;--- 
                                     |
CC2               &lt;-------&gt;   CC2 &lt;---