https://nextjs.org/docs/app/guides/package-bundling

インストール

npm i @next/bundle-analyzer

next.config.js

const withBundleAnalyzer = require('@next/bundle-analyzer')({
  enabled: process.env.ANALYZE === 'true',
})
 
module.exports = withBundleAnalyzer(nextConfig)

機動

ANALYZE=true npm run build