Howtoforge published a guide explaining how to use apt to install PHP 5.6-8.2 with PHP-FPM and FastCGI mode for ISPConfig 3.2 on Ubuntu 18.04 to 22.04.
How to install PHP 5.6 and 7.0 - 8.2 with PHP-FPM and FastCGI mode for ISPConfig 3.2 with apt on Ubuntu 18.04 - 22.04
When using ISPConfig, by default, you only have the main PHP version for your distribution.
