Using 4k Images

All of my uploaded photos are 4k resolution, which is obviously not ideal for loading times. I’m basically wondering if there’s a magical solution to use 4k photos in the media library, but dynamically load a smaller scaled / cropped version, without storing it that way in the media library.

If that’s not possible, what’s the next best solution? Should I use:

add_theme_support( 'post-thumbnails' );

And simply define the sizes I would use? I’m using the Genesis framework, and noticed that wasn’t added to the starter theme by default, and wasn’t sure if there was a reason. I’m basically looking to upload 4k photos no matter what, and serve them in the most optimized way (both performance on loading times, and organization in the media library).

Any information on modern approaches to doing this, what could be coming in core to help this, etc, would be greatly appreciated!