Downloading and installing macOS Sierra 10.12 involves a specific sequence of actions, as Apple now provides older operating systems as disk images rather than direct App Store downloads for modern Macs Apple Support 1. Downloading the macOS Sierra DMG
Now that you have a bootable installer, you can proceed with the installation: download macos sierra 1012 dmg file install
Apple provides official links for older macOS versions. Avoid unofficial sites to prevent security risks. Downloading and installing macOS Sierra 10
If you cannot find a legitimate DMG: