Once you have the file, you may need to prepare it for installation or create a bootable drive:
Macs from late 2009 to mid-2017 that cannot officially run macOS Mojave or later rely on High Sierra as their last supported OS. Models like the MacBook Pro (Mid 2012) and Mac mini (Late 2012) run excellently on 10.13.6. download macos high sierra 10.13 6 dmg file
If you already have an earlier version of High Sierra (e.g., 10.13.1) and only need to reach 10.13.6, you can download the macOS High Sierra 10.13.6 Combo Update directly from the Apple Support Downloads page. Once you have the file, you may need
Locate your USB drive in the left-hand sidebar, right-click it, and select . Locate your USB drive in the left-hand sidebar,
Maximum compatibility with professional legacy software requiring a 32-bit architecture backdrop. Method 1: The Official Apple Route (App Store & Terminal)