Anno 2070 is a rather dated game and used to be really hard to look at while being on anything above 1080p... fortunately, recent update made that no longer a problem!
So, without further ado, just do the following:

- Navigate to the %AppData%/Roaming/Ubisoft/anno2070/Config and open engine.ini;
- Find the line saying UIScalePercentage (if you don't see it, make sure the game has been updated and launched at least once);
- Its default setting is 100. By changing it you can adjust the UI to your resolution. For 1440p I would recommend using 125 or 150, for 4k and higher - at least 200;
- Save the edit and exit;
- Enjoy the game!

Proof: screenshots of the game menu at 100%[i.imgur.com] and at 125%[i.imgur.com], taken by yours truly)

Credits to the Reddit post by the user ziegenpeter2 for the original find!