Grant permissions to the specified site design

• command: spo sitedesign rights grant -i|--id <id> -p|--principals <principals> -r|--rights <rights>
• id: site design ID
• principals: array of principals to whom the specified permissions should be granted
• rights: permissions that should be granted. Allowed values View
• requires connection to the SharePoint tenant admin site

For more information see the Grant-SPOSiteDesignRights cmdlet in the November release of the SPO PowerShell.