Change page title size – Twenty Twenty Four

Hi, I am using the Twenty Twenty Four theme, and the page title shows as an H1 heading, but when I try to change the font size for H1, the title of each post changes accordingly, yet the title of my size at the top of the page is always the same.

How do I change that?

Edit: To make my post clearer. In this preview of the theme, I want to change the font size of the words Twenty Twenty Four on the top left: https://i0.wp.com/themes.svn.wordpress.org/twentytwentyfour/1.2/screenshot.png?w=post-thumbnail&strip=all