There is a document library with many nested folders containing items, total of 791 items. There is a plan to flatten the library (move items out of folders and end folder use), and we have site columns and site content types defined and ready to use. The plan is to copy the current library (structure and content) and work on the copy to create the mature library.
I am familiar with being a site collection admin on an on-premises installation and thus using Save document library as template function along with saving the item data/content. And then from the apps creation function/page, find the doc lib template and create the doc lib with the same 791 items. I would then work on the copy.
But the SP Online in the modern experience does not have these functionalities to my knowledge and there is even information that library copying in this way is discouraged. (I can imagine that to be true with a library containing something like 10-15 thousand items.) I believe that the current practice is that a library should be restructured using the original library, which is making too many users nervous: you always make a copy and work on that.
What's the new practice of duplicating a doc lib with its item content which will have changed column/site content type structure, but possibly the same views that still work within the new field structure?
Can I save the lib template, but just the structure--no content--then do an item copy from original lib to lib copy, with file blob and metadata transfer and expect SharePoint to handle the adjustments on changed metadata, preserving columns where column name and datatype are identical?
Helpful advice appreciated.
