Some sites (e.g., OSBoxes, Techsviewer) provide pre-made virtual disk images (VDI/VMDK) for macOS. These are often easier than finding a raw ISO.
- Download the official installer from the Mac App Store (or Apple's support page).
- Use a terminal command to convert the
.app to an ISO/DMG.
- Use Apple Configurator 2 for external restores or use createinstallmedia on Apple Silicon Macs; virtualization prefers UTM.
hdiutil detach /Volumes/macOS