macOS High Sierra (10.13) is widely considered one of the last "golden" versions of macOS. It is the final version to support 32-bit applications natively without compromise, making it a vital holdout for users with older software or legacy Mac hardware.
If you are looking for a Raw download—meaning a DMG or ISO file rather than an App Store installer—you likely need it for a hackintosh build, a Virtual Machine (VM), or to create a bootable drive for a Mac that no longer has a working App Store connection.
Here is how to get it safely and convert it into the format you need.
.pkg, go to Applications.Install macOS High Sierra.app → Show Package Contents → Contents/SharedSupport – there you’ll find InstallESD.dmg (the raw disk image)..dmg to:
dd or Disk Utility)Double-click the .dmg file. Inside, you will typically find a file named Install macOS High Sierra.app. Drag this into your /Applications folder.
Do not run it from the mounted DMG.