Customize webpack configuration of React App created with Create-react-app

webpack.config.js

const path = require('path');
const CopyWebpackPlugin = require('copy-webpack-plugin')

module.exports = {
    entry: {
        main: './src/index.js'
    },
    output: {
        filename: 'main.js',
        path: path.resolve(__dirname, 'dist')
    },
    module: {
        rules: [{
                test: /\.css$/,
                use: [
                    'style-loader',
                    'css-loader'
                ]
            },
            {
                test: /\.(png|svg|jpg|gif)$/,
                use: [
                    'file-loader'
                ]
            },
            {
                test: /\.(woff|woff2|eot|ttf|otf)$/,
                use: [
                    'file-loader'
                ]
            }
        ]
    },
   plugins: [ new CopyWebpackPlugin([{from: './src/lib/legacyLib.js'}])]
};