0- you must copy the downloaded macOS.app installer into your desktop.
1- you have to ensure that you have enough disk space for running the full process.
2- Open terminal. using spotlight search type “terminal” and press enter. then start typing the following terminal commands:
3-Command 1: create a dmg container on the desktop of a size (15 BG) named “Monterey.dmg”: –
hdiutil create -o ~/Desktop/Monterey -size 15000m -volname Monterey -layout SPUD -fs HFS+J
4-Command 2: mount the Monterey.dmg container into your device: –
hdiutil attach ~/Desktop/Monterey.dmg -noverify -mountpoint /Volumes/Monterey
5-Command 3: Create a bootable macOS Monterey installer into the created dmg container (N.B. You must have install macOS Monterey.app into your desktop as described before in step 2): –
sudo ~/Desktop/Install\ macOS\ Monterey.app/Contents/Resources/createinstallmedia –volume /Volumes/Monterey –nointeraction
6-Command 4: detach the created bootable dmg container: –
hdiutil detach /Volumes/Install\ macOS\ Monterey
7- Command 5: Convert dmg to cdr container: –
hdiutil convert ~/Desktop/Monterey.dmg -format UDTO -o ~/Desktop/Monterey.cdr
8-Command 6: convert cdr to the bootable iso image: –
mv ~/Desktop/Monterey.cdr ~/Desktop/Monterey.iso
Ref: https://www.itech4mac.net/virtualmachines/how-to-convert-macos-installerapp-to-a-bootable-iso-using-terminal