Is it possible to freeze a section to the first view?

I want to do something like this website here:

https:// sliders. dk/en

Where the first section is fixed to the first view, no matter the screen size.
I am guessing that the image is probably something like the background image and you can just freeze that.

But I can’t seem to figure out a way to make the first section fill up the first view, whether it’s on PC or mobile, perfectly so that the section below with its own background does not appear in the first view.

Could anyone help?