It is not real 4K in any material way due to having a final master at 2K. Studios have upscaled the 2K image to 4K and retouched the content for your 4K UHD TV. You should see some visual improvement over a standard 1080p Blu-ray. Check the information below to see if the studios have upgraded the video with HDR or added immersive Dolby Atmos or DTS:X audio tracks.
Shot in 3.4K
VFX Rendered in 2K
Digital Intermediate at 2K*
fantastic beasts ultra hd
The adventures of writer Newt Scamander in New York's secret community of witches and wizards seventy years before Harry Potter reads his book in school.
This was released in theaters in 3D, unless WB made a separate 4K master it means Fantastic Beasts has a 2K DI. I have read no official word from the studio/director/editor that there is a 4K master.