Option to share in Whatsapp LIGHTBOX

You can share an image seen via a lightbox, but the lightbox functionality belongs to the host site. It does not get shared, only the image is shared. The only way to share lightbox itself is if the entire WP page could be embedded in social media. AFAIK that is not possible. You can provide share buttons for your preferred social media, but that does not prevent users from using the image anywhere else they might like. Technical restrictions are largely ineffective. Your intellectual property is protected by copyright laws in most jurisdictions, but the onus is upon you to enforce it.

Thank you for the reply.

So how can I provide whatsapp button?

It partly depends on where you want the button to appear. But in general, construct a normal anchor link to WhatsApp API using the appropriate URL. Include a unique class attribute you can use to style the link to look like a button. This is assuming you can achieve what you want with a basic GET request.

If the API requires more data than can be sent via GET, construct a form of hidden fields containing the necessary data, along with one visible button field. The form should use POST method or whichever method the API requires.