public static FontUIResource applyCustomScaleFactor( FontUIResource font ) {
		if( !isUserScalingEnabled() )
			return font;

		float scaleFactor = getCustomScaleFactor();
		if( scaleFactor <= 0 )
			return font;

		float fontScaleFactor = computeScaleFactor( font );
		if( scaleFactor == fontScaleFactor )
			return font;

		int newFontSize = Math.max( Math.round( (font.getSize() / fontScaleFactor) * scaleFactor ), 1 );
		return new FontUIResource( font.deriveFont( (float) newFontSize ) );
	}
Applies a custom scale factor given in system property "flatlaf.uiScale"
to the given font.
flatlaf-core/src/main/java/com/formdev/flatlaf/util/UIScale.java