private void setGlobalFontSizeOverride(int fontSize) {
		UIDefaults defaults = UIManager.getDefaults();

		Set<Entry<Object, Object>> set = defaults.entrySet();
		for (Entry<Object, Object> entry : set) {
			Object key = entry.getKey();

			if (key.toString().toLowerCase().indexOf("font") != -1) {
				Font currentFont = defaults.getFont(key);
				if (currentFont != null) {
					Font newFont = currentFont.deriveFont((float) fontSize);
					UIManager.put(key, newFont);
				}
			}
		}
	}
Allows you to globally set the font size (don't use this method!)
Ghidra/Framework/Gui/src/main/java/generic/theme/laf/LookAndFeelManager.java