Image-minimizer-webpack-plugin keep aspect-ratio

Question

I'm using the Image-minimizer-webpack-plugin like this:

generator: [
  {
    type: 'asset',
    preset: 'webp',
    implementation: ImageMinimizerPlugin.sharpGenerate,
    options: {
      encodeOptions: {
        webp: {
          quality: 10,
        },
      },
      resize: {
        enabled: true,
        width: 4000,
        height: 4000,
      },
    },
  },

How can I preserve the original aspect-ratio of the image?

I didn't find anything in the documentation: https://webpack.js.org/plugins/image-minimizer-webpack-plugin/

Thank you