Change my font only on top of one Image

I am new to CSS and I am trying to create some changes to my site.I am trying to change the font size only when displayed on phone, and only on one page:https://raspberry-hibiscus-59n4.squarespace.com/?p

I want to change the fonts that are on the first picture (the quote)

Thank you in advance for your help

Each page will have different ID. So you need to find ID of that page. See how to: https://beaverhero.com/squarespace-how-to/#HowtoFindPageID

Next, to use CSS for only phone, you use@media screen and (max-width:640px) { Enter CSS Here }

Final, your CSS should be

@media screen and (max-width:640px) {
body#collection-5d01486ebc3e4800010a9633 div#page-5d02792fe3ffe700014a8bd0 h1 {
   font-size: 20px;
   font-family: Helvetica;
   color: red;
}
}

@amardeepatherapy :D

Thank you very much for your help

@amardeepatherapy It worked?