sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume (Replace "MyVolume" with the name of your USB drive.)
Additionally, ensure that you have a backup of your important files and data, as a clean installation will erase your Mac's hard drive. download macos catalina 10.15.7 full installer
Need help? Leave a comment below (or visit Apple’s official discussion forums). If you’re using a patched Catalina on unsupported hardware, always check the patcher community’s latest updates. sudo /Applications/Install\ macOS\ Catalina
Terminal (softwareupdate) — useful for scripting or if App Store link doesn’t work the system refuses to run it.
Apple code-signs installers with a certificate that expires. The certificate for the Catalina installer expired in October 2022. If you downloaded it after that date, the system refuses to run it.