We are looking for copy a content type from one site collection to another.
Both site collection having different site template.
How to copy content Type from one site collection to another in SharePoint Online using PowerShell?
You can use PowerShell CSOM to export and import Content Type in SharePoint Online.
There are some articles about this topic for your reference:
Export Import Content Types In SharePoint Online Using PowerShell
SharePoint Online: Export-Import Content Type using PowerShell