The game has very aggressive post processing sharpening which looks terrible with DLSS and especially DLAA. The sharpening can be removed or reduced with one .ini entry:

Go to:
C:\Users\USERNAME\AppData\Local\DuneSandbox\Saved\Config\WindowsClient

2. Find:
Engine.ini

3. Add in the bottom:
[SystemSettings]
r.tonemapper.sharpen=0

This will disable the sharpening entirely. To only reduce it set it to something between 0.1 and 1 (0.5 to half the strength)

My personal sweetspot for 1440p DLAA is 0.3