You can change the font with some Custom CSS, like this:
body {
font-family: Tahoma, Verdana, Segoe, sans-serif;
}
That’s called a font-stack, and it relies on your visitors having the Tahoma font installed on their computer (most people do, according to the resource I used to get that stack). If a visitor doesn’t have the first font, they’ll see the next one as a fallback, and so on.
To add that CSS, you can use the Additional CSS panel in the Customizer (assuming you’re running at least WordPress 4.7) or with something like the Jetpack Plugin using the Custom CSS Module