Can I set a default Facebook or Twitter link preview image for my products?

Yes, you can do so. 

In the Setting tab, there is an option "Set default link preview image for products". You can select to use the first product image (a.k.a the feature image), the last product image, or the default options (use the last 3 product images). Our code snippet in your theme.liquid will automatically pick a suitable image. 

Please note that we will try to match the best ratio of link preview image suggested by Facebook (1200px x 630px width-to-height ratio of 1.91:1) and Twitter (minimum size 300px x 157px width-to-height ratio of 2:1).  

If you're looking for the bulk update, this feature can help you to do so by setting the last product image as the link preview image. You can upload the link preview image as the last product image. If the default Facebook link preview image and custom link preview image are both set for a product, the custom image will win. 

Currently, we support Facebook and Twitter link preview for your products. Please note that you must install our code snippet in order to use this function. ( How?)