I have added sound to the above link. Although I want to decrease layered audio file sound by 50% and also retain the original sound of the video
You can use the e_volume transformation parameter for each layered audio. For example:
Here is the link to the documentation - https://cloudinary.com/documentation/transformation_reference#e_volume
Demo sample: https://res.cloudinary.com/demo/video/upload/e_volume:-50/dog.mp4
Hope this helps.