AutoSSL for hostname, localhost, postfix, etc...

[avrodvr]

How does renewal for these certificates work? I received the following warning from certwatch...

Code Select Expand

################# SSL Certificate Warning ################

Certificate for hostname 'my.hostname.com', in file (or by nickname):
    /etc/pki/tls/certs/localhost.crt

The certificate needs to be renewed; this can be done
using the 'genkey' program.

Browsers will not be able to correctly connect to this
web site using SSL until the certificate is renewed.

##########################################################
                                 Generated by certwatch(1)

I'm aware that localhost.crt is a self-signed certificate I can update via openssl in CLI, but I'm curious why it doesn't update automatically and how/if other server certs such as hostname and postfix are updated. Are they updated automatically?