PsychoPy’s GUI has adopted a fundamentally timeline-based approach (like video or audio editing software), rather than one based on spatial layout (like PowerPoint, or E-prime). i.e. it doesn’t offer the approach you are after.
An alternative is OpenSesame: https://osdoc.cogsci.nl
OpenSesame can use PsychoPy’s code behind the scenes to actually run the experiment, but implements the spatial GUI you are after. This is the beauty of open source code: people can adapt it and do different things with it. The spatial approach comes with its own limitations of course (particularly for time-varying stimuli). Perhaps you should try both and see which you actually prefer in practice.