A standard bluray player has 1080p avc, vc-1 or mpeg2 decoder to playback a disc. Therefore any disc played on it must use one of the those format.
It simply won't understand a 4k hevc disc.
A UHD bluray player has the 4k hevc decoder along with the previously mentioned decoders. Keep in mind that UHD bluray players are now required to use Cinavia, which will block a non original disc if present. DVDFab has a tool to remove it, but it does convert the audio to a non compressed PCM stream (last time I checked). This means less overall space for the video content on the disc.
Streaming boxes like the Shield TV (2019) do not have the Cinavia requirement. For playing back a uhd disc with a minimum of transcoding, your best bet is a streaming box with a streaming server. I use a Shield TV (2019) pro with a plex server and I can play UHD content without any transcoding. I only need to use my UHD bluray player for a Dolby Vision and Dolby Atmos disc. Video containers like mkv just can't handle both of them at the same time at this point in time. Work is being done to change that.