Qt6 Offline Installer [better]
Example qt-install-script.qs :
Because official pre-built Qt 6 offline binaries are restricted for open-source users, you must use alternative strategies if you require an offline workflow: Qt6 Offline Installer
For absolute independence from installers, you can download the Qt6 source code archive from the official Qt open-source mirror and build it completely offline. Example qt-install-script
Downloading multi-gigabyte frameworks across dozens of developer workstations strains office networks. A single offline package saves massive amounts of data. Qt6 Offline Installer