How to add big-image parameter to make image zoomable in .xlsx file

Welcome to the ODK forum, @Sonali! We're glad you're here. When you get a chance, please introduce yourself on this forum thread. I'd also encourage you to add a picture as your avatar because it helps build community!

Do you mean when asking a user to upload an image - question type of image? Or when displaying an image as media as part of the question?