All services installed are already configured and no additional changes are required unless you know very well what you are doing.
The Apache Web Server
The Apache configuration file resides in /etc/httpd/conf.
Additional configuration files related to the loaded Apache modules reside in /etc/httpd/conf.d.
Each domain name or a subdomain created in SPanel has its own virtual host file located at /etc/httpd/vhosts/domain.com.conf
Custom configurations to each vhost can be done by adding the extra content in a random_name_here.conf file located in /etc/httpd/conf.d/userdata/user_name/domain.com/
The individual PHP-FPM Apache configuration files for each SPanel account reside in /etc/httpd/conf.d/php-fpm/.
The MariaDB Database Server
MariaDB is installed via the official MariaDB repository. This is a default installation via DNF with the configuration file in /etc/my.cnf in case you need to make any changes.
PHP and PHP-FPM
The PHP versions are installed and updated via the Remi repository. SPanel supports all versions from PHP 5.6 to the latest one.
The main PHP configuration file for each of the versions is located in /etc/opt/remi/php*/php.ini while the PHP-FPM configuration files for each of the accounts on the server are located in /etc/opt/remi/php*/php-fpm.d/
Additional Services Installed
Each SPanel server also has Pure-ftpd, Exim, Dovecot, SpamAssassin, BIND, Memcached, NodeJS installed via the DNF package manager.