where is package json laravel8 code example

Example 1: package.json laravel best

mix.stylus('resources/assets/stylus/app.styl', 'public/css');

Example 2: package.json laravel best

mix.sass('resources/assets/sass/app.scss', 'public/css')
   .options({
        postCss: [
            require('postcss-css-variables')()
        ]
   });