This is a typical installation steps for installing php 7.x on Centos, the latest version as of writing is PHP 7.4

yum install -y yum-utils epel-release
yum install http://rpms.remirepo.net/enterprise/remi-release-7.rpm 

To install PHP required versions based on your needs install the required version. For example to install php71

yum-config-manager --enable remi-php71 # php71 for php 7.1, php72 for php 7.2 etc. 
yum install -y php php-common php-opcache php-mcrypt php-mysql php-cli php-gd php-curl  # installation of base php modules