Followed the steps given on the official google app engine page for installing the sdk for php->
https://developers.google.com/appengine/docs/php/gettingstarted/hell
On windows:
Download php at here https://www.php.net/downloads.php Example the path for download D:\php72
Run app:
dev_appserver.py --php_executable_path="D:\php72\php-cgi.exe" path_app/app.yaml