The process of building custom applications and tools that interact with Microsoft SharePoint, including SharePoint Online in Microsoft 365.
Hi John ,
Unfortunately, there is currently no OOTB method to automatically add a template to many libraries at once. There are some workarounds for your reference:
1, Use PowerShell.
2, Use content type (Highly recommended).
3, Use "Add template" (Need to operate one by one manually).
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