Hello @Navya Ande (MINDTREE LIMITED) thanks for reaching here, Just wanted to confirm if you looking to export the entire index or just the results from a specific query(ies), please let us know to help you better on this.
If you are looking for results from specific query to export to pdf or excel then when performing a search query, you get back a JSON response of results. These could easily be mapped to an excel file or written to a PDF with specific formatting.
Refer to below links:
Generating PDF from json and json-schema
c# 4.0 - How to convert .json file to excel in c#