Powershell script to copy whole Sharepoint site structure (Site, subsites, folder, subfolders) to a new site

I have developed a Document Centre structure (site, subsites, folders and subfolders) in SharePoint online and I need this replicated as a Record Centre. I have a PowerShell script to copy each subsite with its folders from the Document Centre and create it in the Record Centre, but I need help to add the sub folders and permissions as well. I also need advice on best practice to create the Record Centre Structure (types of template to use for subsites and how to move documents from document center to record center.)