Add the authorbio shortcode automatically.

authorbio-shortcode-auto-include.php

<?php

add_filter( 'the_content', function( $content, $post_id ) {

	// Run only on blog posts.
	if ( 'post' !== get_post_type( $post_id ) ) {
		return $content;
	}

	// Do not run on the old blog posts, where we already have placed our author bio.
	if ( has_shortcode( $content, 'authorbio' ) ) {
		return $content;
	}

	// Add our authorbio. do_shortcode() will be executed with the priority of 11.
	return $content . '[authorbio]';

}, 10, 2 );