Hi Sneha,
Unfortunately mendix export excel module provides basic styling not very advance
alternatively you can use below module .
It provides advance styling and manipulation
Advanced Excel in this module unlike excel export module you don't create whole template once
instead you create cells and add it to workbook and then export
sample is also given in the module
Hi Sneha,
you can add your custom style for borders in excel-export , read 6.6 in below doc
https://docs.mendix.com/howto/integration/using-the-excel-exporter/