Where is the config files and why isn’t it anywhere in the top level folders, etc?
The initial project doesn’t require the file to exist because you just created a project with fresh “default” settings that don’t require any config.
Just create it yourself. it’s even mentioned in the README:
Many aspects of a Vue CLI project can be configured by placing a vue.config.js file at the root of your project. The file may already exist depending on the features you selected when creating the project.
(emphasis mine)
Edit: now to be found here: https://cli.vuejs.org/config/#global-cli-config