how to download FaceTime app on iMac version 12.12.6
how to download/update the FaceTime app on iMac version 12.12.6
iMac, macOS 10.12
Question marked as
No such thing as macOS 12.12.6.
Current macOS 12 version is 12.2.1 FaceTime is pre-installed and cannot be removed. Should be available from the Applications folder in Finder.
If you actually mean macOS 10.12.6 Sierra, then it's also built in, and cannot be deleted. FaceTime requirements - Apple Support
Should be available in the Finder or Launchpad icon on the dock.