Cubase 11.0.20/Nuendo 11.0.20 introduces a new custom scaling option available under Preferences ▸ General ▸ HiDPI Settings:

By setting the "Application Scaling" the GUI of Cubase/Nuendo can be scaled to 25% and 50% of the current Windows scaling.

• The scaling option applies to all screens. It is not possible to set a different scaling for each monitor. 
• It is not possible to set a scaling below 100%.  For example, if Windows is set to 125% and Cubase/Nuendo to -50%, the result will be 100%. 
• Cubase/Nuendo GUI components that are managed by Windows like the menu bar, load/save dialogues and all other Windows UI elements do not follow the "Application Scaling" set in Cubase/Nuendo. 
• Cubase/Nuendo needs to be restarted after applying a new scaling.