Update: Resource Manager can reverse engineer configurations and also check for configuration drift. This is a very powerful capability. For my purposes, I have not had to work with Terraform that much.
I will leave the script below, but suggest reviewing resource manager and point out that my Terraform skills are basic.
Here is a script to build out a two networks in Oracle Cloud Infrastructure. In each network, there are three subnets — dmz, app, and db. There is a single VM created called jump in the dmz of primary. What is here works, but overall it is work in progress since it is not complete. The purpose at this point, it just an example of Terraform use.