Although not exactly ultra-wide, on my 27" screen, the font-size with maximised window (2500px horizontally) would compute to ~22px for the submitted website. While that’s noticeable bigger compared to a narrow view port, I’m not sure that would qualify as “very large”. To me, it looks alright.
The main container’s width on their website also doesn’t scale infinitely, so on a very wide screen you’d have a lot of blank space on both sides.
That being said, it might still be reasonable to set a break point (or use CSS clamps) and prevent further font-size growth beyond a certain point.
Yes how is the viewport size really relevant? A sensible site would have a max column width for any paragraph. So if I have a 4000px wide viewport and view a 500px wide column of text, it has to be the same size as the 500px column of text also if the browser window is just 1000px?
The main container’s width on their website also doesn’t scale infinitely, so on a very wide screen you’d have a lot of blank space on both sides.
That being said, it might still be reasonable to set a break point (or use CSS clamps) and prevent further font-size growth beyond a certain point.