@Damned-Ananas
The code you show does not work as the three QLabels are not part of any layout.
So setting
hLayout->setStretch(0, 1);
hLayout->setStretch(1, 1);
hLayout->setStretch(2, 4);
does not affect the labels, unless you are doing something else which you did not show.
And, as @JonB said above, until the layouts are applied and the widget is shown, you can't trust the widget's geometry you receive from geometry(), width() or height() as these values are generic/default values based on your settings and not how the widget actually looks when being rendered in some window or parent widget.
So please show your complete/actual code (and/or try what @JonB suggested)