A. Check the PHP version from the DA GUI

1. Log into DA server

2. Navigate to Extra Features >> CustomBuild

3. Click the Edit Options tab. You will see the PHP versions that are installed on your server:

directadmin php versions
DirectAdmin PHP versions

B. List PHP versions from command line

Log into the DirectAdmin server and run the command:

# /usr/local/directadmin/custombuild/build options | grep PHP

You will see all the versions installed (the default one and the additional ones):

[[email protected] ~]# /usr/local/directadmin/custombuild/build options | grep PHP
PHP (default): 7.4 as php-fpm
PHP (additional): 8.0 as php-fpm
PHP (additional, 3rd): 7.0 as php-fpm
PHP (additional, 4th): 7.2 as php-fpm
[[email protected] ~]#

Links:
How to change PHP site version in DirectAdmin