Dolby Digital Plus 7.1 for iTunes downloads

When I look at the audio options for many of the movies available from iTunes on my iPhone I see the option for Dolby Digital Plus 7.1 audio available. But, when I get home and look at the same movies through iTunes on my gaming laptop, which is connected to a DD+ 7.1 audio system, I only see the option for Dolby 5.1.

Is the DD+ 7.1 only available when streaming through a device like the AppleTV (like the 4K video) and not when downloading the video from iTunes?

If so, are there any plans to make the 7.1 channel audio available in the downloads in the future?