Update WordPress post title from an ACF field value on save. (Advanced Custom Fields)

sync_acf_post_title.php

<?php
/**
 * Update Custom Post Title from an ACF field value on post save.
 *
 * Triggers on save, edit or update of published posts.
 * Works in "Quick Edit", but not bulk edit.
 */
function sync_acf_post_title($post_id) {
    $post_type = get_post_type($post_id);
    if($post_type === "custom_post_type") {
		
		$title = 'get_field('ACF_title_field', $post_id);
		
	} else if($post_type === "other_custom_post_type") {

		$title = get_field('ACF_title_field', $post_id));

	} else {
    //if no matching CPT do nothing
		return;
 }
    
    $content = array(
        'ID' => $post_id,
        'post_title' => $title
    );

    wp_update_post($content);
}
add_action('acf/save_post', 'sync_acf_post_title');