As long as the volume of the media is turned down in the mobile phone settings, the sound of WeChat video will be small.

1. Open the settings in the phone.

2. Select sound and vibration, as shown:

3. In the sound and vibration-volume adjustment, slide the volume point to the left, and the sound will be turned down, as shown in the figure:

After this adjustment, the media volume of your mobile phone will be lower, so the voice of WeChat video will be lower.