When you install MySQL on CentOS 8, you will need to install other associated packages as well. It can be easily solved by @ option when you call yum command.

Following command line will install all the associated packages at one shot.

yum -y install @mysql

If you haven't installed PHP and planning to use it. Following example will help you to install all other associated packages with MySQL.

yum -y install @php

Once installation is compete, you will need to run following commands to start the service automatically.

systemctl start mysqld
systemctl enable --now mysqld
systemctl status mysqld

Regarding the security, you should do is running security script for MySQL: