import * as sass from "sass";
import eleventySass from "@grimlink/eleventy-plugin-sass";

module.exports = function (eleventyConfig) {
    eleventyConfig.addPlugin(eleventySass, {
        sass,
        outputPath: "",   // Optional subdirectory
        includePaths: ["node_modules"]
    });
}

To install, run

# NPM
npm install --save-dev sass @grimlink/eleventy-plugin-sass
# Yarn
yarn add -D sass @grimlink/eleventy-plugin-sass