font size increase for mobile view using hueman theme

Hi,

You need to use a child theme.
https://docs.presscustomizr.com/article/239-using-a-child-theme-with-hueman

Add the following in your child theme style.css

@media screen and (max-width:768px){
h2 {
    font-size: 50px !important;
}
p {
    font-size: 30px !important;
    line-height: 1.2 !important;
}
}

Make adjustments to the font-size values according to your requirement.
You need to clear mobile browser history every time you make changes.

Thank you