HTML Guide for imagesizes
For rel="preload" and as="image" only, the imagesizes attribute is a sizes attribute that indicates to preload the appropriate resource used by an img element with corresponding values for its srcset and sizes attributes.
For rel="preload" and as="image" only, the imagesizes attribute is a sizes attribute that indicates to preload the appropriate resource used by an img element with corresponding values for its srcset and sizes attributes.