Apple no longer provides direct public download links for .dmg installers of older macOS versions. The official method provides an .app file. However, you can obtain the official installer and optionally convert it to a .dmg .
Look for – the link usually opens the App Store. Download Mac Os High Sierra 10.13.6 Dmg
Because Apple no longer lists High Sierra prominently on the App Store for modern Macs, obtaining the requires using specialized terminal commands or Apple's hidden support links. Apple no longer provides direct public download links for
Once the installer app is in your Applications folder, you can create your own bootable media or DMG: Format a USB Drive Disk Utility Download Mac Os High Sierra 10.13.6 Dmg