Hi Kalayani,
As ben suggested, you can achieve it. But Condition for updating the status depends on products existence.
So, First retrieve the Products associated to the request, then change request to Approved if Products exist if not change request to reject.
You should be able to use either the Radio Button widget or the Drop Down widget inside a data view to have the admin select the new value in the UI. If you need to set the value inside a Microflow Change Object action, then you can use ModuleName.EnumerationName.EnumerationValue (i.e. MyFirstModule.ResquestStatus.Approved )