LG Ultrawide 21:9, MBP 2017 no HiDIPI 2560x1080 I have a LG Ultrawide 34WN650 and a 2017 MacbookPro(Big Sur) with both Radeon Pro 560 4 GB
and Intel HD Graphics 630 1536 MB. I have purchased a USB-C to Displayport  cable, a USB-C to HDMI cable, QuickRes and SwitchResX.
Do you know how to get HiDIPI 2560x1080 resolution? QuickRes has a HiDIPI 1280 X 540 that does nothing when I click it. 1280 X 540 looks excellent but it is 16:9 not 21:9. I can't use custom resoultions in SwitchResX because they are &quot;Not installed&quot; after save and restart. The video and pictures are excellent in normal 2560x1080, but the fonts are extremely bad.
I have tried:

https://medium.com/@nvucuong/macos-blurry-texts-on-an-external-full-hd-monitor-d2a955c25607

https://www.chanhvuong.com/4403/fix-blurry-text-on-mac-using-external-non-apple-monitor/

sudo defaults write /Library/Preferences/com.apple.windowserver.plist DisplayResolutionEnabled -bool true)
With the help of Stephan Madrau, the creator of SwitchResX I have found a solution for my problem:

half of the non HiDPI resolution is the HiDPI resolution, so I am using SCALED 3840 x 1620 non HiDPI --&gt; 1920 x 810 HiDPI. It is a bit big.. but it is looking fresh and crisp.