Hey dude, you'll be surprised how easy it is. Look, just go to this library site https://directory.audio/ and select what you need through the filter in the search. It takes no more than 5 minutes. Here are collected all the popular and not so popular sound effects, music and melodies that you may need. You don't have to worry about copyright, the Creative Commons license under which all audio on the site is released allows you to legally use it
