Certificate question

Does the single server install have any self signed certificate by default at all ?

I wondered if I should install anything like this:
How to Enable Self-Signed Certificates for Local Apache Webserver - LINUX - Yeah Hub

Do I need to do stuff ?
What is recommended

I suggest you read about this

Ok so I read it.
What does it do ?

I’m trying to figure out if I need this or not. Mainly the site coming up that says unsecure or perhaps a warning for users to click to continue due to security etc.

Is this what this instruction solves ? AND does it make the site now https ? Or something .