With the USB C - 3.5mm jack (USB 3.2 Gen 1) adapter from 3MK you can output audio, but it is not guaranteed that you can also record audio with it. The adapter is primarily designed for lossless audio transmission for playback. Whether recording via a stereo AUX cable on the mobile phone is possible depends on the respective device and its USB-C audio input support, which is not available on all smartphones.

This means: Theoretically, a mobile phone with USB-C and the corresponding hardware/recording function can record audio via the 3.5mm input, but in practice this is not guaranteed for all devices. The adapter itself is not an active recording device, but a pure audio cable for input or output.