To enable or disable Office Viewer integrated in the Microsoft Edge browser, toggle the switch against 'Open Office Files in the browser' setting.

While you won't be able to edit Excel files with the iPad's Quick Look file viewer, you will be able to view them and even copy and paste data from them.

1] Convert DBF to XLSX or XLS in Microsoft Excel Microsoft Excel users can convert DBF files to Excel formats within Excel. It supports dBASE files to open, view, edit, print, and convert.