If your Mac is running an older supported version:
: Minimum 2 GB (4 GB recommended) Storage : 14.5 GB available space download macos high sierra 10.13 6 dmg file
This is the safest way to get the full installer. You can find the link on the official Apple Support page . Clicking the High Sierra 10.13 If your Mac is running an older supported
If you only get a "stub" installer (around 20MB), you may need to run it and let it download the rest of the data, then find the files in /macOS Install Data before the computer restarts. 2. Using Terminal (macOS Catalina or later) download macos high sierra 10.13 6 dmg file
Apple offers a hidden link that opens the Mac App Store directly to the High Sierra page.