When I play 4D HDR content using the Apple TV App on my Mac Pro, it's smooth with real HDR contrast.
I do not know how to play Disney + HDR content using a browser.
I will be getting another Apple 4K TV box to connect to the Pro Display XDR to see how good Disney + HDR content is.
Are you setting HDR Video (P3-ST 2084) preset on your MacBook Pro 16?
How many RAM and VRAM on your machine?
No, I'm using the `Pro Display XDR (P3-1600 nits)`. My MBP 16 has 64GB RAM, I'm not sure about VRAM. It's a maxed-out machine.