Apache MPM worker configuration and prefork mpm configuration

I installed virtualmin LAMP on CentOS 7. By default virtualmin comes with prefork MPM , first of I can’t find its configuration file under /etc/httpd/conf.d/ , should I create it myself with directives like :

StartServers 10
MinSpareServers 10
MaxSpareServers 20
ServerLimit 2000
MaxRequestWorkers 1000
MaxConnectionsPerChild 8000

Or I need to add them somewhere else ?

Other than that, what if I wanted to change to mpm_worker instead of mpm_prefork. Will it break anything ?