Hi Trey,
Try adding add-author-rel to the class list of the Block.
Adding Custom Classes: https://wordpress.com/support/wordpress-editor/adding-additional-css-classes-to-blocks/
Then, add this snippet:
function db_rerender_link( $block_content, $block ) {
if(!is_admin() && ! empty( $block['attrs']['className'] ) && strpos( $block['attrs']['className'], 'add-author-rel' ) !== false ) {
$my_search='href="';
$my_replace='rel="author" href="';
$new_content = str_replace($my_search, $my_replace, $block_content);
return $new_content;
}
return $block_content;
}
add_filter( 'render_block', 'db_rerender_link', 10, 2 );
Adding PHP: https://docs.generatepress.com/article/adding-php/#code-snippets