Two curves plot the contrast of HD and 4K-resolution images versus detail fineness. At 1920, HD's fine detail is maximized, but the lower contrast approaching the cutoff point reduces the perceived sharpness. Shooting at 8K and 12K resolutions for lower resolution  release would see an analogous result; the outputted program at 4K, say, would not see the expected lowering of contrast approaching 4096, and thus greater fineness.
{"Image ImageWidth": "720", "Image ImageLength": "540", "Image BitsPerSample": "[8, 8, 8]", "Image Compression": "Uncompressed", "Image PhotometricInterpretation": "2", "Image Orientation": "Horizontal (normal)", "Image SamplesPerPixel": "3", "Image XResolution": "72", "Image YResolution": "72", "Image PlanarConfiguration": "1", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS6 (Macintosh)", "Image DateTime": "2020:10:11 18:03:16", "Image ExifOffset": "256", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "394", "Thumbnail JPEGInterchangeFormatLength": "6249", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "720", "EXIF ExifImageLength": "540"}