Change leaves duration from hours to days in SAP Fiori app

In general, customizing Fiori applications involves customizing the parent SAP application. So, if in the application, it defaults to hours then the Fiori app will also inherit the default behavior and show it in hours.

Go ahead and change it to days, it will impact your Fiori app and the app will also start showing in days.

In case you cannot afford to make a change in SAP application, then you need to handle it in a custom manner which will require you to have a custom implementation in place.