Is it possible to change the main variant image on Also Bought?

By default, the image of the first variant is displayed for consistency and we cannot modify this behaviour.

When you use the drop-down variant selector to switch from one variant to another, the image displayed is changed accordingly.

If we displayed the main product image by default, customers might be confused after changing the variant using the drop-down and then switching back to the first variant.

Please note that you can choose the first variant easily in your Shopify admin, in the product section by reordering the variants. First you have to access the specific variant by clicking 'Edit:

And then you can just reorder them according to your needs: