The core post Author block does not currently link to the author page. The following code filters the contents of the post author block and dynamically wraps the block with a link to the author page.
add_filter( 'render_block', function ( $block_content, $block, $instance ) {
if ( ( $block['blockName'] ?? '' ) !== 'core/post-author' ) return $block_content;
if ( is_author() ) return "<h1>$block_content</h1>";
$post_id = $instance->context['postId'];
$author_id = get_post_field( 'post_author', $post_id );
$author_url = get_author_posts_url( $author_id );
return <<<htm
<div class="wp-block-post-author--link">
<a href="$author_url">$block_content</a>
</div>
htm;
}, 10, 3 );