not sure if Copilot can help here - we need to wait until the product is released. What's possible is that e.g. Copilot can extract text of the document and with the VBA function of the model you can generate PowerPoint Slides. This is already available with Bing Chat Enterprise (maybe for you) at https://bing.com/chat
Use the prompt like this: I want you to write me VBA code for a PowerPoint presentation about the following text: "INSERT TEXT HERE". I want to have 5 slides Just press ALT+F11 in PowerPoint and add a Module to the "Presentation". If you are not familiear with this, just ask Bing Chat Enterpris, it will guide you through. Later you can copy the slides to your existing presentation.