Using UIManager to resize the default Icon size?

I’m teaching a group basic Java and one student has used J Option panes to include images in a “make your own adventure” type game.

JOptionPane.showMessageDialog(null, “add text”, “Doge”,
new ImageIcon(new URL(“”)));

However, is their a way to add a simple UIManager line at the start that will resize the images he finds from the URL’s and make them fixed.

We previously did this to change the button text like so.

UIManager.put(“OptionPane.okButtonText”, “Proceed”);

I want to see if it can be taught this way as to not over complicate, as I want the students to be focusing on the basics of the language, and these simple lines at the start allow them to customise without going off topic too bizarrely.