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:
mysql_secure_installation