Yes! The infobox element is nothing else than an internal text element. That means, you have to change the attributes before
JXG.Options.infobox.strokeColor = 'blue';
JXG.Options.infobox.fontSize = 24;
const board = JXG.JSXGraph.initBoard('jxgbox', {
boundingbox: [-5, 5, 5, -5],
axis: true
});
var p = board.create('point', [1, 2]);
board.infobox.setAttribute({strokeColor: 'red'});