Hi @sns ,
According to your description, you want to clone a site collection and create a new site collection with this as a template.
You can use 3rd party tools. More information, you can click this.
Note: The third-party product that this article discusses is manufactured by a company that is independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of third-party products referenced in this article.
Thanks,
Echo Du
========================================
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.