Does this support Ultrawide resolutions at 60hz?

[seanbperiod]

I read that the top external resolution is supported at 30hz, so I'm wondering if ultrawide resolutions are supported at 60hz?

And related: Is the imac 4k internal display at 60 or 30hz?

 

[Precursor]

Supports 3440x1440 through HdMI @60 Hz
https://forums.macrumors.com/threads/is-3440x1440-at-60hz-possible-for-macbook-2015.1886597/

4k iMac is 60 Hz