The last Word MS printed "user manual" I have is from WinWord 6.0 in 1994.
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As Stefan says, MS stopped printing manuals decades ago. They don't even produce a single web site that documents ALL the features in Word.
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If you want a single introductory "user manual" for "Office 2021 Home and Student" you will have to go to a book store. I suggest you spluge and buy individual books for each of the applications you want to learn. "Special Editions" if you can find them. I haven't been in a book store for a few years now so I don't know what is on the shelves these days. The thing is, a truely comprehensive book for Excel would have to be HUGE, since it would also have to cover PowerQuery, PivotTables, and PivotCharts. Each of which is functionally huge.
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Trying to find one book for Office 2021 is proving to be hard. You may have to settle for a "365" book, and you would have to be careful to get one for a version of 365 released in 2021.
Here is a sample hit from Amazon
https://www.amazon.com/Best-Sellers-Microsoft-Office-Guides/zgbs/books/4127
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Here is a possible book (I haven't seen it myself), but personally I would try to find it in a physical book store to preview it before buying https://www.amazon.ca/MICROSOFT-EXCEL-BEGINNERS-POWER-USERS-ebook/dp/B094K3CRXF
463 pages is very short for a comprehensive cover of both Word and Excel.
My Que "Special Edition Using MS Word 97" is 1244 pages.
My Osborne "Complete Reference Word 2000" is only 837 pages.
My Que "Special Edition Using MS Office for Windows 95" (Word, Excel, PowerPoint and Schedule+" is 1048 pages.
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