How to keep window size proportional to the screen its appearing

[umen]

How does Qt handle screen resolution and size to keep proportion between the Qt window
and the screen size , for example when I set window size on my development pc

[ChrisW67]

I'm not sure I understand your question.

Qt reports the resolution reported by the underlying operating system (see QDesktopWidget). Top level windows are given a default size based on their contents and size hints. You can explicitly set the size (QWidget::setGeometry()) or persist the window geometry (see QWidget::saveGeometry() or QWidget::saveState()) between runs.