A Cloud Optimized GeoTIFF (COG) is a regular GeoTIFF file, aimed at being hosted on a HTTP file server, with an internal organization that enables more efficient workflows on the cloud. It does this by leveraging the ability of clients issuing HTTP GET range requests to ask for just the parts of a file they need - read more here - Cloud Optimized GeoTIFF
As I understand it, I could simply point an online map viewer at a web folder of COG files and the imagery would be displayed. Esri should support COG files across their platform.
Here is an online demonstration - COG-Explorer