Many third-party tools are available that help you quickly generate PowerPoint from the .net core application. Let me give you a couple of links that may help you.
- https://support.syncfusion.com/kb/article/8755/how-to-create-a-powerpoint-file-in-asp-net-core
- https://www.youtube.com/watch?v=OSGwosNnN0o
- https://www.e-iceblue.com/Introduce/free-presentation-component.html
I used Syncfusion components in my projects, and they work great.
Note:- I do not work for Syncfusion Company.