If you’re referring to the site title, you would copy the alx_site_title function form the parent theme functions.php file to a child theme functions.php file:
function alx_site_title() {
// Text or image?
if ( ot_get_option('custom-logo') ) {
$logo = '<img src="'.ot_get_option('custom-logo').'" alt="'.get_bloginfo('name').'">';
} else {
$logo = get_bloginfo('name');
}
$link = '<a href="'.home_url('/').'" rel="home">'.$logo.'</a>';
if ( is_front_page() || is_home() ) {
$sitename = '<h1 class="site-title">'.$link.'</h1>'."\n";
} else {
$sitename = '<p class="site-title">'.$link.'</p>'."\n";
}
return $sitename;
}
Then change the link variable to reflect the new target:
$link = '<a href="https://www.google.com/" rel="search" target="_blank">'.$logo.'</a>';