The generate_site_title_output
allows allows us to alter the HTML of our site title.
Example
If we don’t want a link surrounding the title:
add_filter( 'generate_site_title_output', function( $output ) {
return sprintf(
'<%1$s class="main-title" %3$s>
%2$s
</%1$s>',
( is_front_page() && is_home() ) ? 'h1' : 'p',
get_bloginfo( 'name' ),
'microdata' === generate_get_schema_type() ? ' itemprop="headline"' : ''
);
});