Hi there,
the Site Title should only be set as a H1 if there is no other H1 being used on the page. As you front page doesn’t have one you could add this PHP snippet:
add_filter( 'generate_site_title_output','tu_frontpage_h1_title' );
function tu_frontpage_h1_title() {
printf(
'<%1$s class="main-title" itemprop="headline">
<a href="%2$s" rel="home">
%3$s
</a>
</%1$s>',
( is_front_page() ) ? 'h1' : 'p',
esc_url( apply_filters( 'generate_site_title_href', home_url( '/' ) ) ),
get_bloginfo( 'name' )
);
}
Adding PHP: https://docs.generatepress.com/article/adding-php/
For the other pages you could use a GP Page Header:
https://docs.generatepress.com/article/page-header-overview/
In particular you could add the title in the Page header content like so <h1>{{post_title}}</h1>
that will pull in the title of the post automatically.