To determine which permissions an application will request, it depends on the functionality required by the application. The necessary permissions are determined by development team of the application. The type of content or data the application needs to be access within M365 will also impact the required permissions.
Currently, to know which permission will be needed, it all depends on the respective application team who will be developing that application to know which permission they required to implement that functionality.
To get details about Microsoft Graph permissions reference, you can refer to this documentation.
Hope this helps.
If the answer is helpful, please click Accept Answer and kindly upvote. If you have any further questions about this answer, please click Comment.