sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume (Replace "MyVolume" with your USB drive's name) Installation via Recovery Mode

If you are currently on a Mac, you can download the full installer directly. Visit the macOS Catalina page on the App Store . Click "Get" to download the "Install macOS Catalina.app" to your Applications folder.

diskutil unmountDisk /dev/diskN