In the sounds tab! I do audio requests, I can get anything off youtube. If you want to do it yourself, instructions for how to do it safely and probably legally are here: https://scratch.mit.edu/projects/1162307925/ Idk if it works on anything other than Windows but you can try. You probably just have to download the right app from github.
https://www.youtube.com/shorts/jivVVj7OCY8 The video I got it from
