For graphics work, of course the answer might be different and I'm no expert. Personally I think screen size does matter, and I've noticed a fair improvment going from 28 to 32.
With 4K it feels like I have to do a lot of tabbing between apps on a single monitor.
But I get people’s experiences obviously vary since display preferences are extremely subjective and overall it seems like the 27” 5K and 32” 6K fans are in the minority.
I have 20/20 vision and a pretty normal desk setup. I run my 32 4K at 100% scaling in Windows, and while I could maybe push it down a little smaller, some of the least PPI-aware interfaces and text would start to be too small.
If you're running 6K scaled to 150%, you basically just have a slightly sharper 4K monitor - effectively 0 extra space. If you're not running it scaled, I'm betting you're sitting closer to the monitor than is recommended for long term use (or have like 20/10 vision).