I used google font https://fonts.google.com/specimen/Jost
in my project.

If I use font-family: ‘Jost’; Jost font is applied.

If I use font-family: ‘Jost’, sans-serif; Jost font is not applied

As per my understanding by default Jost font should be applied, if it is not available sans-serif should be used.

Please let me know if you know the reason.