I see you are using QT 6.8.0. In that case add:

qt_policy(SET QTP0004 NEW)

to your CMakelists.txt file, inbetween "qt_add_executable" and "qt _add_qml_module" sections. That should solve the warnings. (https://doc.qt.io/qt-6/qt-cmake-policy-qtp0004.html)

As for the Color.qml import. You might try adding it as a module instead of a relative path.