The engine has rendering scaling functions that can be used to improve the situation.
Go to: C:\Users\Your_user_name\AppData\Local\FactoryGame\Saved\Config\WindowsNoEditor and edit: Engine.ini
Add this line:
where XXX is your scale.
Example for 2k display. Set the screen resolution in the game 1920x1080 to increase the interface. And the variable r.ScreenPercentage = 150. This will increase the rendering resolution by 50% to 2880x1620, which will give good quality on a 2k display. (it is possible and more if the power of gpu allows)
This works like a scaling slider in other games.
Why the developers will not add it to the game menu that's the question. All the functionality is already in the engine, you just need to add a menu item.
Sorry for the English, this is a google translator.