If you are looking for a direct DMG download for archival purposes and do not trust third-party sites, see Method 2 to create your own.
This guide will walk you through the process of downloading and installing macOS Catalina 10.15.7 from a DMG (Disk Image) file. Please note that it's essential to obtain the DMG file from a trusted source, such as the official Apple website or a legitimate software repository. macos catalina 10.15.7 dmg
Download the installer; it will appear in your /Applications folder as "Install macOS Catalina.app." If you are looking for a direct DMG