Install Qt 6 using MSYS2

pacman -Syu
pacman -S base-devel
pacman -S mingw-w64-x86_64-qt-creator
pacman -S mingw-w64-x86_64-qt6-base
pacman -S mingw-w64-x86_64-qt6
pacman -S mingw-w64-x86_64-clang
pacman -S mingw-w64-clang-x86_64-toolchain
pacman -S mingw-w64-x86_64-clang-tools-extra
pacman -S mingw-w64-x86_64-gdb

Optional Dependencies:

pacman -S mingw-w64-x86_64-cmake
pacman -S mingw-w64-x86_64-gdb
pacman -S mingw-w64-x86_64-ninja
pacman -S mingw-w64-x86_64-qbs
pacman -S mingw-w64-x86_64-qt6-doc
pacman -S mingw-w64-x86_64-qt6-quicktimeline
pacman -S mingw-w64-clang-x86_64-tidy

References
https://wiki.qt.io/MSYS2
https://packages.msys2.org/package/mingw-w64-x86_64-qt-creator
https://packages.msys2.org/package/mingw-w64-x86_64-qt6-base
https://packages.msys2.org/group/mingw-w64-x86_64-qt6
https://packages.msys2.org/package/mingw-w64-x86_64-clang
https://packages.msys2.org/group/mingw-w64-clang-x86_64-toolchain
https://packages.msys2.org/package/mingw-w64-x86_64-clang-tools-extra
https://packages.msys2.org/package/mingw-w64-x86_64-gdb
https://packages.msys2.org/package/mingw-w64-clang-x86_64-tidy?repo=clang64