npm install sass-loader node-sass --save-dev

node_modules/react-scripts/config/webpack.config.js

            {

              loader: require.resolve('file-loader'),

              // Exclude `js` files to keep "css" loader working as it injects

              // its runtime that would otherwise be processed through "file" loader.

              // Also exclude `html` and `json` extensions so they get processed

              // by webpacks internal loaders.

              exclude: [/\.(js|mjs|jsx|ts|tsx)$/, /\.html$/, /\.json$/],

              options: {

                name: 'static/media/[name].[hash:8].[ext]',

              },

            },

            // ** STOP ** Are you adding a new loader?

            // Make sure to add the new loader(s) before the "file" loader.

          {

            test:/\.scss$/,

            loaders: ['style-loader', 'css-loader', 'sass-loader']

          }