Making subpanels in the UI

The easiest way to split the user interface into several visual groups is to registers several separate panels in the Blender Python API and merge them by setting the same "bl_category" parameter. In this case, we get some arranged vertically panels, which can be independently collapsed and expanded.

Read more: https://b3d.interplanety.org/en/making-subpanels-in-the-ui/