Googled “Considering conflict mpm_worker for mpm_prefork:”
Found this:
https://stackoverflow.com/questions/46258053/change-apache-mpm-from-prefork-to-worker
https://serverfault.com/questions/682272/cant-enable-mpm-prefork-with-apache-2-4-on-ubuntu-14-04
It seems it needs one module or another to be enabled or disabled…the links show you how to do that
This shows to install the PHP 7.3 there are other things that need to be installed
https://askubuntu.com/questions/1148129/how-do-i-enable-php-7-3-in-apache2