Update existing site design

• command: spo sitedesign set -i|--id <id> -t|--title [title] -d|--description [description] -w|--webTemplate <webTemplate> -s|--siteScripts <siteScripts> -m|--previewImageUrl [previewImageUrl] -a|--previewImageAltText [previewImageAltText] --isDefault [isDefault]
• id: The ID of the site design to update
• title: The new display name of the updated site design
• description: The new display description of updated site design
• webTemplate: The new template to add the site design to. Use the same enumeration as in spo sitedesign add
• siteScripts: A new array of one or more site scripts. Each is identified by an ID. The scripts will run in the order listed
• previewImageUrl: The new URL of a preview image
• previewImageAltText: The new alt text description of the image for accessibility
• isDefault: true if the site design is applied as the default site design; otherwise, false
• requires connection to a SharePoint site

For more information see the information on the Update Site Design REST API at https://docs.microsoft.com/en-us/sharepoint/dev/declarative-customization/site-design-rest-api#updatesitedesign