If you're a developer, you might be able to access older versions of macOS through the Apple Developer portal.
In Terminal, run this command: sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume . macOS High Sierra - App Store - Apple
If you're a developer, you might be able to access older versions of macOS through the Apple Developer portal.
In Terminal, run this command: sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume . macOS High Sierra - App Store - Apple