Image Conditional Logic functionality makes it possible to change main product image conditionally upon selection in custom option. It works almost like Formula Conditional Logic, but instead of formulas in rules you select images.
The related modal form can be accessed by clicking on this icon in the Builder.
This is how it looks like:
There is one major setting:
Enable/disable image conditional logic functionality
⚠️ IMPORTANT: Option's changing image functionality does not work when Image Conditional Logic is enabled! Only this or only that will work, not together!