Hi Leonard,
I don’t think it’s a good idea, as then you will have many site titles, it’s not great for SEO, and might get the bot confused.
But if you insist, you can try this PHP snippet:
add_filter( 'generate_site_title_output', function( $output ) {
return sprintf(
'<%1$s class="main-title" itemprop="headline">
%3$s
</%1$s>',
( is_front_page() && is_home() ) ? 'h1' : 'p',
esc_url( apply_filters( 'generate_site_title_href', home_url( '/' ) ) ),
get_the_title()
);
});