Upgrade AspNet Core 5 Application

we have files management app to stores files in different file formats Which are Save in application wwwroot folder and path in sql server database. We need Job to be done as fallows 1. being excel files are uploading successfully to our application we need functionality to read and manipulate the Excel files which are uploaded to our application. 2.We want File/Photo/Images/Excel/pdfs Files to be upload from android mobile phones to our present FileManagement app.
3. To send Files of different formats to and from our present FileManagement application to Different whatsapp numbers ......
will uploaded related files if might needed or helpful in explaining required....Thanks