Hi @ntfromchicago,
@Maria_Gosur is right, this feature doesn’t work any more, it’s clearly broken.
My designs are 1440px wide and my MacBook 16" is 3072px wide (1536px 2x). Prototype is set to “Presentation (Fill)” but none of the 4 options scale the design UP to fill width, they all scale it down or leave it with black bars. And I’ve tried “None” and “Custom” mode as well, same. I even tried to modify the URL code by hand without luck.
This is how the presentation modes looked like until recently, and the Fill - Scale down or up to fill always worked for me:
I’ve surely read through every single discussion that Google ever found on this topic (barely exaggerated 
) and all either talk about the old “Fill - Scale down or up” mode or come to no working solution.
Figma THIS IS A SERIOUS BUG AND SHOW STOPPER … showing designs on the TV in the conference room or sending it to clients that might have large displays will result in a thin stripe with black bars.
The only solution I’ve found is to upscale all my art boards by hand, which even with the scale tool is very time consuming because components won’t scale correctly and have to get adjusted one by one. But this is urgent.
If anyone knows a real solution for this issue please come forward, I’ll reward you with the biggest digital hug the internet has ever seen!
Cheers, Chris