Dear Monty1726,
Good day to you!
I hope you are doing well. Thanks for reaching out to our Microsoft Community Forum. We will be happy to help you.
According to your description, you have implemented intelligent versioning in SharePoint and would like to know whether it will apply to existing document libraries and how to enable it.
Based on information from the official Microsoft documentation, there are currently no separate settings available to directly enable intelligent versioning for existing document libraries. Here is the article for your reference: Plan version storage for document libraries - SharePoint in Microsoft 365 | Microsoft Learn.
However, site owners and administrators may apply the new version controls to existing sites and document libraries using PowerShell. This method allows you to configure versioning settings across libraries that were created before the feature was implemented.
If you need assistance with using PowerShell to enable versioning for existing libraries, feel free to let me know, and I can guide you through the process.
If you have any questions, feel free let us know for further assistance.
Thank you for your understanding. Your cooperation and contributions are greatly appreciated.
Kind Regards,
Nahid Sultan