It depends on what version of Xbox One you have. On the original Xbox One game consoles, 4K Blu-ray disc playback is not supported. You can only stream 4K content. However, on Xbox One S and One X consoles, UHD 4K Blu-ray disc playback is supported because these newer machines were updated with the necessary hardware.
To play blu-ray discs on Xbox One S or X, you’ll need to download Microsoft’s Blu-Ray Player App. It’s free and the first time you pop in a blu-ray movie, it’ll prompt you to download it.