I needed to create a bootable ISO image of macOS to do some testing of desktop software and scripts on a clean macOS install using VMWare Player. I knew you could do this, I just didn't know what the current steps were. Can you download this ISO image somewhere? How does it work?
After some searching I found this is the current way with macOS Ventura at least (YMMV if it's a different version):
# Creates Empty Disk:
hdiutil create -o /tmp/Ventura -size 16384m -volname Ventura -layout SPUD -fs HFS+J
# Mounts created disk:
hdiutil attach /tmp/Ventura.dmg -noverify -mountpoint /Volumes/Ventura
# Creates install media:
sudo /Applications/Install\ macOS\ Ventura.app/Contents/Resources/createinstallmedia --volume /Volumes/Ventura --nointeraction
# Unmounts disk image:
hdiutil eject -force /Volumes/Install\ macOS\ Ventura
# Creates CDR file:
hdiutil convert /tmp/Ventura.dmg -format UDTO -o ~/Desktop/Ventura
# Converts CDR to ISO:
mv -v ~/Desktop/Ventura.cdr ~/Desktop/Ventura.iso
# Cleans up files:
rm -fv /tmp/Ventura.dmg