How to use PostCSS autoprefixer through PostCSS-cli?

Question

I came across the PostCSS autoprefixer docs,

I didn't get what arguments to pass with.

Input File path --use use autoprefixer -d Output CSS path

npx postcss ./assets/styles.css -- use autoprefixer -d build

The docs didn't make sense.

module.exports = {
    "plugins" : [
        require('autoprefixer')({
            browsers: ['> 1%', 'last 4 versions'],
        }),
        require('postcss-import'),
        require('postcss-partial-import')({
            prefix: '_'
        }),
        require('postcss-nested'),
        require('postcss-each'),
        require('postcss-each-variables'),
        require('postcss-for'),
        require('postcss-custom-media'),
        require('postcss-at-rules-variables'),
        require('cssnano')({
            preset: ['default', {
                discardComments: {
                    removeAll: true,
                },
            }]
        }),
        require('cssnano-preset-advanced'),
        require('@fullhuman/postcss-purgecss')({
            content: ['./**/*.html']
        }),
    ]
}