Sometimes you need a raw recovery DMG to fix a bricked Mac. Apple provides these indirectly via the Internet Recovery system, but you can also extract them.
If you are already running macOS Mojave or a newer version, you can use the built-in command-line tool to download the complete, official installer from Apple's servers. Download Macos Catalina 10.15.7 Dmg File
Note: This downloads an InstallAssistant.pkg file. Double-clicking this file on a compatible Mac will unpack the standard "Install macOS Catalina.app" directly into your folder. Sometimes you need a raw recovery DMG to fix a bricked Mac
Your Mac is too new (e.g., M1 MacBook Pro 2021). Apple blocks Catalina downloads on hardware that never supported it. Download Macos Catalina 10.15.7 Dmg File
diskutil unmountDisk /dev/diskN
Only download macOS Catalina 10.15.7 from Apple’s servers directly or using Apple’s official tools.