Hello @jason_long
If you are asking about security with php 5, please find answer as follows:
PHP 5.4 is not patched since 2015 and PHP is not patched since 2016. This means that any website using PHP 5.4 or 5.5 or older versions are highly vulnerable to these attacks.
For more info related to PHP 5 or 7 you can find details in below shared article:
https://serverguy.com/magento/how-to-protect-magento-stores-running-on-old-php-versions/
Apart from that Magento latest version(2.3) not supports PHP 5 and Magento has well documented for Technology stack requirements:
https://devdocs.magento.com/guides/v2.3/install-gde/system-requirements-tech.html
Please have look once and let me know if you need any other info.
Please accept as solution if it works. Thanks