Hi MakiHayakawa1, I am Paulo and I'd like to help.
The Ctrl + Shift + ~ release then type n or Shift + n for the upper case would only work in Microsoft Word. If you intend to type it in the browser and your keyboard doesn't have a Numpad, then a workaround would be to press Windows + Ctrl + o to open the on-screen keyboard. Press Alt on your keyboard then click on 164 or 165 from the on-screen keyboard
ñ = Alt (Physical key) + 164 (Click on OSK)
Ñ = Alt (Physical key) + 165 (Click on OSK)