Haven't totally automated my entire job but a small portion of what I do is configuring a fresh aws account some core services (SMTP, NTP, LDAP etc etc) and the associated VPC configurations before handing it off to the devs.

Wrote a pretty simple python script that takes some inputs, cidr range, account name, jira ticket etc, and sets up all the terraform, ansible groupvars, ssh key generation, secret storing and a few version control check-ins. Reduced the footprint from a few hours to literally less than one minute.