yarn add react-app-rewired

"scripts": {
  "start": "react-app-rewired start",
  "build": "react-app-rewired build",
  "test": "react-app-rewired test"
 }

yarn add @babel/plugin-proposal-decorators metro-react-native-babel-preset -D

// .babelrc
{
 "presets": ["module:metro-react-native-babel-preset"],
 "plugins": [
  [
   "@babel/plugin-proposal-decorators",
   {
    "legacy": true
   }
  ]
 ]
}

// config-overrides
const { getBabelLoader } = require('react-app-rewired');

const path = require('path');

module.exports = function override(config, env) {
 const babelLoader = getBabelLoader(config.module.rules);
 const pwd = path.resolve();
 babelLoader.include = [path.normalize(`${pwd}/src`)];
 // use babelrc
 babelLoader.options.babelrc = true;
 
 return config;
};

{
 "name": "my-react-project",
 "version": "0.1.0",
 "private": true,
 "dependencies": {
  "react": "^16.5.2",
  "react-app-rewired": "^1.6.2",
  "react-dom": "^16.5.2",
  "react-scripts": "2.0.5"
 },
 "scripts": {
  "start": "react-app-rewired start",
  "build": "react-app-rewired build",
  "test": "react-app-rewired test"
 },
 "eslintConfig": {
  "extends": "react-app"
 },
 "browserslist": [
  ">0.2%",
  "not dead",
  "not ie <= 11",
  "not op_mini all"
 ],
 "devDependencies": {
  "@babel/plugin-proposal-decorators": "^7.1.2",
  "metro-react-native-babel-preset": "^0.48.1",
  "webpack-bundle-analyzer": "^3.0.3"
 }
}