対処
$ sudo amazon-linux-extras install php7.2
$ sudo yum -y install php php-mbstring
$ rpm -qa |grep php
php-json-7.2.34-1.amzn2.x86_64
php-cli-7.2.34-1.amzn2.x86_64
php-common-7.2.34-1.amzn2.x86_64
php-pdo-7.2.34-1.amzn2.x86_64
php-fpm-7.2.34-1.amzn2.x86_64
php-7.2.34-1.amzn2.x86_64 ★
php-mysqlnd-7.2.34-1.amzn2.x86_64
php-mbstring-7.2.34-1.amzn2.x86_64
$ rpm -ql php-7.2.34-1.amzn2.x86_64
/etc/httpd/conf.d/php.conf
/etc/httpd/conf.modules.d/15-php.conf
/usr/lib64/httpd/modules/libphp7-zts.so
/usr/lib64/httpd/modules/libphp7.so ★
/usr/share/httpd/icons/php.gif
/var/lib/php/opcache
/var/lib/php/session
/var/lib/php/wsdlcache
$ sudo vi /etc/httpd/conf/httpd.conf
LoadModule php7_module modules/libphp7.so ★
$ sudo systemctl reload httpd.service