Per standard, the Clerk.io extension for Magento fetches images with a size of 210x210 px.
This can be changed in the following file:
In the top of this file, the
$imageWidth variables control the height and width of each image:
Change these values to the size you want images to have, and save the file.
Then go to my.clerk.io -> Data Sync and run a new sync, by clicking Start Sync.
Your new images will now be synced.