Appliances, bathroom accessories, beds, cabinets, chairs, and couches.
Graphisoft maintains an archive of legacy libraries for migration purposes. You can often find the "Archicad 12 Library" inside the "Goodies" or "Add-ons" section for older versions, or specifically in the Migration Kit section of the Help Center. Archicad 12 Library Download
When searching for "Archicad 12 Library Download," you will likely encounter third-party file-sharing blogs, torrents, and sketchy forums. Archicad 12 Library Download
If you are looking for specific objects (furniture, windows, doors) that were common during the Archicad 12 era: BIMcomponents.com Archicad 12 Library Download
When downloading, check the "compatible version" list to see if it can be imported into 12. 3. ArchiUp.com
The Ultimate Guide to Archicad 12 Library Downloads: Restoring and Optimizing Legacy BIM Projects