As your applications get larger or interfaces become more complicated, it can get a bit cumbersome to define all elements programmatically. The good news is that Qt comes with a graphical editor Qt Designer (or Qt Creator) which contains a drag-and-drop UI editor — Qt Designer. In this PyQt5 tutorial we'll cover the basics of creating Python GUIs with Qt Designer.
Creating applications with Qt Designer
Using the drag-drop designer to develop your apps
Start with “First steps with Qt Designer”