How to set Angular CLI Development Server Port via .env

.env

DEV_SERVER_PORT=4201

package.json

{
  "name": "my-angular-project",
  "version": "0.0.0",
  "scripts": {
    "start": "node run-env"
  },
  "dependencies": {
    "@angular/animations": "9.1.3",
    "@angular/common": "9.1.3",
    "@angular/compiler": "9.1.3",
    "@angular/core": "9.1.3",
    "@angular/platform-browser": "9.1.3",
    "@angular/platform-browser-dynamic": "9.1.3",
    "@angular/router": "9.1.3",
    "core-js": "2.6.11",
    "rxjs": "6.5.4",
    "tslib": "^1.9.0",
    "zone.js": "0.9.1"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "^0.901.3",
    "@angular/cli": "^9.1.3",
    "@angular/compiler": "^9.1.3",
    "@angular/compiler-cli": "^9.1.3",
    "@types/node": "~10.12.0",
    "dotenv": "^8.2.0",
    "ts-node": "~7.0.0",
    "typescript": "~3.5.3"
  }
}

run-env.js

const dotenv = require('dotenv');
const child_process = require('child_process');

const config = dotenv.config()
const DEV_SERVER_PORT = process.env.DEV_SERVER_PORT || 4200;

const child = child_process.exec(`ng serve --port=${DEV_SERVER_PORT}`);
child.stderr.on('data', err => console.error(err.toString()));
child.stdout.on('data', data => console.log(data.toString()));