How to turn the background sound into a billiard room when talking on Apple's mobile phone?

According to Apple official website's data, if you want to turn the background sound into billiard room sound when talking on Apple's mobile phone, you need to open the system settings, find the auxiliary function, select audio-visual in hearing, click to enter the background sound, and turn on the billiard room background sound.

Background sound is to add simulated scene sound during the call to create the illusion that the caller is in the scene.