Hello,
Not entirely sure if this is the MacBook Air model your wife has but if so, yes it should work.
https://support.apple.com/kb/SP813?viewlocale=en_US&locale=en_US
"Video Support
Simultaneously supports full native resolution on the built-in display at millions of colors and:
- One external 6K display with 6016-by-3384 resolution at 60Hz at millions of colors, or
- One external 5K display with 5120-by-2880 resolution at 60Hz at millions of colors, or
- Up to two external 4K displays with 4096-by-2304 resolution at 60Hz at millions of colors
Thunderbolt 3 digital video output
- Native DisplayPort output over USB‑C
- VGA, HDMI, and Thunderbolt 2 output using adapters (sold separately)"
I hope this helps.