If you are looking for something very specific. You can try creating your own plugin code to extract what you need.

class PluginGetFileSize {
  private file: string;

  constructor(file: string) {
    // receive file to get size
    this.file = file; 
  }
  apply(compiler: any) {
    compiler.hooks.done.tap(
      'Get File Size',
      (stats: any) => {
        // Get output file
        const file = stats.compilation.assetsInfo.get(this.file); 
        
        // Verify if file exists
        if (!file)
          return console.log('File not exists');

        // Get file size
        const fileSizeInBytes = file.size;

        // only used to convert
        const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB']; 

        // Get size type
        const sizeType = parseInt(Math.floor(Math.log(fileSizeInBytes) / Math.log(1024)).toString());

        // Get size of file using size type
        const size = Math.round(fileSizeInBytes / Math.pow(1024, sizeType));

        // Here you can log, create a file or anything else
        console.log(`${this.file} has ${size} ${sizes[sizeType]}`);      
      }
    );
  }
}

For this simple example, i only need to pass one file path to use the plugin but if you need, you can pass more files here.

module.exports = {
  //...
  plugins: [
    new PluginGetFileSize('YOUR-OUTPUT-FILE.js'),
  ],
};

I believe there must be some packages with similar functions like:

• size-plugin
• webpack dashboard you can learn more about this here
• webpack analyse
• bundlephobia to visualize your dependencies size in a simple way
• webpack visualize
• webpack-bundle-analyzer that you brought yourself
• lighthouse use to analyze your entire application in different aspects

Also, check out webpack official docs Bundle Analysis section. Especially if using webpack 5, as some common tools still not supporting it.

bundle-stats is a great tool.