Double-click the file to mount it. Inside, you will typically find a .pkg or .app file. If it is a .pkg , run it to extract the "Install macOS Sierra" application into your Applications folder. 2. Creating a Bootable USB (Recommended) For a clean installation, use a USB drive (at least 8GB).
From the startup manager menu, select the drive.
To download the macOS Sierra 10.12.6 DMG file, you can use the official direct link from Apple Support How to Download and Install macOS Sierra 10.12.6 Mac Os Sierra 10.12.6 Dmg File Download
Developers or IT professionals may need this version for testing older applications. Key Features of macOS Sierra
Type your Mac's administrator account password when prompted (no characters will show on screen as you type) and press . Double-click the file to mount it
If you are searching for the you likely fall into one of three categories:
If your hardware allows, consider upgrading to a newer, supported OS, such as macOS High Sierra (10.13) or Catalina (10.15), to ensure better protection and app compatibility. To download the macOS Sierra 10
Double-click the downloaded macOS_Sierra.dmg file.
Once the installer window loads, select first to erase and format your target drive (select APFS or Mac OS Extended (Journaled) ). Exit Disk Utility and click Install macOS .