I tried adding
<var name="height">530</var> inside
<var name="gallery"></var> as this is the parameter to add height in fotorama as per the documentation but my declaration is not applying. I tried doing s:up and c:f but nothing works.
Found the answer.
The height option (for fotorama gallery), even though is added in the documentation, is not being pulled because the variable itself is not being used in GalleryOptions.php. Magento Automatically considers the 'product_page_image_medium' for main image height and 'product_page_image_small' for thumbnail. You can add and update how it is set in GalleryOptions.php in Magento_Catalog.