Guidance for using variable font in CSS

[danglingneuron]

Salam:
I have tried the variable font but don't know the settings to elongate the words as you have done on your website.

src: url('fonts/digitalkhatt/digitalkhatt-cff2.otf') format('opentype-variations');

I have had no success using CSS properties or the font variation axis tags. I am also not aware of any custom axis tags you might have used in the font for the variations to work. Please provide guidance!

/* with their CSS properties /
font-weight: 637;
font-stretch: 100;
/ with the font-variation-settings property */
font-variation-settings: "wght" 637, "wdth" 100;