> Sometimes higher resolution can even reduce the bitrate
I cannot imagine how this could ever be true. Have you experienced it actually happening for the same content at the same encoding settings?
"bitrate" = file size / duration. There is no reason why increasing the resolution should ever make a video more compressible. This is completely different from the 10-bit situation you described, which takes place because you're storing data in a different format.
You could choose to encode a higher resolution copy of a video at a lower bitrate, but it's nothing an encoder will do by default, and it should always result in the higher resolution version looking worse.
I cannot imagine how this could ever be true. Have you experienced it actually happening for the same content at the same encoding settings?
"bitrate" = file size / duration. There is no reason why increasing the resolution should ever make a video more compressible. This is completely different from the 10-bit situation you described, which takes place because you're storing data in a different format.
You could choose to encode a higher resolution copy of a video at a lower bitrate, but it's nothing an encoder will do by default, and it should always result in the higher resolution version looking worse.