Using the 3D mode allows you to check how your design will actually look in reality.
Use this toggler in the menu to switch between modes.
We always recommend you to constantly switch between 2D and 3D modes during the designing process to check if the location or colours of the object suit your style. Your device might struggle with processing the design in the 3D mode so make sure to get back to 2D.
If your device for some reason doesn’t process the 3D view, make sure you have enough free space and none of the other applications is conflicting with the Planner 5D app.