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 "Not installed" after save and restart. The video and pictures are excellent in normal 2560x1080, but the fonts are extremely bad.
I have tried:
sudo defaults write /Library/Preferences/com.apple.windowserver.plist DisplayResolutionEnabled -bool true)