Pref -> styleConfig -> fontStyle:

fontSize, then EnableGlobalFontSize

— notepad++ zoom:

• screen pinch (not reliable!) or
• Ctrl / the-big-PLUS-key-on-far-right. The minus key also works.
• .. On Acer299, it is the blue PLUS key

Note Ctrl / other-PLUS-keys work in Chrome, not in notepad++