This yields a ready for VMs or old hardware.
Since Apple does not provide a native ISO, you must create one yourself using the downloaded .app installer: macos high sierra 10.13 6 iso download
For scripted environments, using the mas (Mac App Store CLI) tool is efficient. This yields a ready for VMs or old hardware
Before downloading, ensure your Mac supports High Sierra. The general rule is that most Macs from 2010 or newer are compatible. : MacBook : Late 2009 or newer. MacBook Pro & Air : Mid/Late 2010 or newer. iMac : Late 2009 or newer. Mac mini & Mac Pro : Mid 2010 or newer. The general rule is that most Macs from
Visit the official Apple Support legacy macOS page and click the High Sierra link to open it in the App Store.
Convert to ISO: hdiutil detach /Volumes/Install\ macOS\ High\ Sierra and then hdiutil convert /tmp/HighSierra.dmg -format UDTO -o ~/Desktop/HighSierra.iso Mac OS High Sierra 10.13 iso : Apple - Internet Archive