How to force fancybox not to open in full screen?

Question

fancyBox

Good afternoon.
On mobile, links to youtube open in full screen like this:

The picture that is in the background is stretched in height by 100% and cut off at the edges.
The video itself, if you run it, takes up only a third of the screen approximately:

But the Youtube window is still large.
How to make the window initially fit the video size, and not the screen size?