Hi, no problem - nothing extra to do as I remember.
PB uses UTF-16 internally. Which means any text field in PowerBuilder can display any Unicode character if your font supports that character. Some fonts included with Windows support specific character sets. You will find support for Spanish ñ in close to all character sets also supporting English A-Z. Can think of one that doesn't support it.
NVARCHAR2 is Oracle's name for Unicode in UTF-16. You just have to learn the keyboard combo for ñ and Ñ and you are good to go.
As soon as you are on NVARCHAR2 you can also handle all the other funny character we use around Europe - my Danish Æ Ø Å - Swedish Ä Ö Å for the same characters. And everything else in Unicode like Japanese, Greek, and Hebrew to name a few. - again, as long as your character set supports those characters.
Enjoy /Michael
TIP: Nice Unicode lookup page https://www.compart.com/en/unicode/
Sample search for ñ delivers https://www.compart.com/en/unicode/U+00F1