Hi Atul,
The standard excel export module doesn't seem to have this option.
But you can achieve this by using a different entity for the export that is preferably session scoped(non-persistable). When the export button is clicked, you copy the data to that entity and use formatDateTime() to create a string of the date or date with the time. Then use the entity to export the data to excel. This way you can model it all yourself and use the standard excel export module. There might also be an export module in the marketplace that does have this option to format or parse data.