Create WhatsApp URL dynamically using ACF Pro from different fields

You can used ACF Pro and adding some custom code to your theme’s functions.php file.

// Add ACF fields
if( function_exists('acf_field_group') ):

acf_field_group(array(
    'key' => 'group_60aaf3a3f3d4a',
    'title' => 'WhatsApp Fields',
    'fields' => array(
        array(
            'key' => 'field_60aaf3aaf3d4b',
            'label' => 'WhatsApp Phone',
            'name' => 'whatsapp_phone',
            'type' => 'text',
            'instructions' => 'Enter the WhatsApp phone number',
            'required' => 1,
            'default_value' => '',
        ),
        array(
            'key' => 'field_60aaf3b9f3d4c',
            'label' => 'WhatsApp Message',
            'name' => 'whatsapp_message',
            'type' => 'text',
            'instructions' => 'Enter the default WhatsApp message',
            'required' => 1,
            'default_value' => '',
        ),
        array(
            'key' => 'field_60aaf3d7f3d4d',
            'label' => 'WhatsApp Link',
            'name' => 'whatsapp_link',
            'type' => 'text',
            'instructions' => 'This field will be dynamically populated',
            'required' => 0,
            'default_value' => '',
            'readonly' => 1,
            'hidden' => 1,
        ),
    ),
    'location' => array(
        array(
            array(
                'param' => 'post_type',
                'operator' => '==',
                'value' => 'post', // Change this to your post type to your post_type_slug
            ),
        ),
    ),
));

endif;

// Function to dynamically generate WhatsApp link
function generate_whatsapp_link($post_id) {
    // Get phone number from theme options
    $whatsapp_phone = get_field('whatsapp_phone', 'option');

    // Get message from post
    $whatsapp_message = get_field('whatsapp_message', $post_id);

    // Encode message
    $encoded_message = urlencode($whatsapp_message);

    // Generate WhatsApp link
    $whatsapp_link = "https://wa.me/{$whatsapp_phone}?text={$encoded_message}";

    // Update the whatsapp_link field value
    update_field('whatsapp_link', $whatsapp_link, $post_id);
}

// Hook to update WhatsApp link when post is saved
add_action('acf/save_post', 'generate_whatsapp_link', 20);

// Shortcode to display WhatsApp link in the frontend
function whatsapp_link_shortcode($atts) {
    $post_id = isset($atts['post_id']) ? intval($atts['post_id']) : get_the_ID();
    return get_field('whatsapp_link', $post_id);
}

add_shortcode('acf_whatsapp_link', 'whatsapp_link_shortcode');