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Hi Zoe,

Block libraries are not shipped with AutoCAD. You have to find and download them yourself.
For example:
https://www.google.com/search?client=safari&rls=en&q=free+autocad+furniture+blocks&ie=UTF-8&oe=UTF-8

Then you can add them to your own block libraries using "Content palette" (in AC 2019 and earlier versions) or using "Blocks palette" (in AC 2020).