You can use pre_get_posts
in your functions file to alter the query
function wpsites_query( $query ) {
if ( $query->is_archive() && $query->is_main_query() && !is_admin() ) {
$query->set( 'posts_per_page', 100 );
}
}
add_action( 'pre_get_posts', 'wpsites_query' );