Using yum-config-manager enable the Remi repository as the default repository for installing PHP different version. Following example for enabling Remi repository.
yum install http://rpms.remirepo.net/enterprise/remi-release-7.rpm
yum-config-manager --enable remi-php73
Example for Install the PHP 73 with all necessary modules will install while installing PHP 73. The following packages are necessary for PHP 7.3.
yum install php php-mcrypt php-cli php-gd php-curl php-mysql php-ldap php-zip php-fileinfo