You need to run yum in order to use PHP after setup your CentOS 7. Even though you have httpd, PHP may need to be installed manually.
First of all, you need to check if you have httpd on your CentOS 8 server as following:
ls /usr/sbin/httpd
If it does not exist, you can install it simple as following:
yum -y install httpd
If everything is okay, please run below commands to install PHP packages you need.
yum -y update sudo yum -y install epel-release yum-utils sudo yum -y install http://rpms.remirepo.net/enterprise/remi-release-7.rpm sudo yum -y update sudo yum -y install php php-common php-devel php-bcmath php-gd php-pdo php-pear php-mysqlnd php-mbstring php-xml tidy php-tidy php-soap php-pecl-apcu php-pecl-ssh2 mcrypt php-mcrypt php-pecl-memcache php-intl php-zip redis ImageMagick-devel sudo yum -y update
Actually I faced below errors while I install PHP packages
No match for argument: php-tidy No match for argument: php-pecl-ssh2 No match for argument: php-mcrypt No match for argument: php-pecl-memcache