Normalmente ctrl + roda de rolagem funcionaria, mas no seu caso, como explicado em Lifehacker :
In order to zoom in, you just press control (Windows) or command (Mac) and the + key. (Technically you're pressing the = key because you'd need to press shift to make a plus, but thinking of it as the + key makes more sense since it's zooming you in.) To zoom out, press control/command -, and press control/command 0 to set things back to normal.