This script can be used to add a custom Field/Column to the Folder Content Type of a List or Document Library. This script also has the functionality to remove the Fields and also to list all the Fields in the Folder Content type for a List or Document Library.
The Folder Content Type is sealed by default. We cannot customize it by adding any custom fields from the UI to the default Folder content type. Only way to do is going programmatic way. In real world, not all the SharePoint users are programmers. This PowerShell script enables the SharePoint users/administrators to simply run the script to accomplish the same.
You can find more All-In-One Script Framework script samples at https://aka.ms/onescriptingallery