Add Webpack Bundle Analyzer plugin to your create-react-app via react-app-rewired.
yarn add --dev react-app-rewire-bundle-analyzer
OR
npm install --save-dev react-app-rewire-bundle-analyzer
In your react-app-rewired configuration:
/* config-overrides.js */
const rewireBundleAnalyzer = require('react-app-rewire-bundle-analyzer');
module.exports = function override(config, env) {
// ...
config = rewireBundleAnalyzer(config, env);
// ...
return config;
}