Hi Brady,
You can use the CSS below to change these
/* for site title */
.slide-bg-section h1{
font-size: 35px;
}
/* for site description */
.slide-bg-section p{
font-size: 14px;
}
/* Home page buttons */
.slide-bg-section .read-more a, .slider .slider-button .read-more a{
font-size: 11px;
}
You can change the px numbers according to your need
Copy and paste the above CSS in Appearance -> Customize -> Additional CSS
Regards