Do you mean you have multiple PowerPoint files and want to organize them to one PowerPoint file grouped by topic? If so, we can merge your multiple PowerPoint files to one file:
On the Home tab of the ribbon, in the Slides group, click the arrow below New Slide, and then select Reuse Slides. In the Reuse Slides pane, click Open a PowerPoint File to merge files.
Then we can use the Zoom for PowerPoint feature in PowerPoint 2016 (This feature is only available for Office 365 Subscriber on Windows) to organize your sliders. When you create a Zoom in PowerPoint, you can jump to and from specific slides, sections, and portions of your presentation in an order you decide while you're presenting.
Create Sections in PowerPoint, then go to Insert > Zoom, select Section Zoom. Select the section you want to use as a Section Zoom. Select Insert. Your Section Zoom will be created.