Yes, I will use PSR-12 formatting if I were to work in your company. But if I write code for myself I will chose what's sensible and maybe this project will show you too that the PSR-12 formatting is nothing but stupid.
Either start it locally with this:
php -S localhost:8080 index.php
Or look up the php docker images. You need php-gd and php version 8.1.2 or higher.