By design WooCommerce only autocompletes orders for downloadable and virtual products. This snippet autocompletes order which has only bookable products with all bookings completed, and has status processing..

wc-bookings-autocomplete-orders.php

<?php
abstract class MaraleAutocompleteOrders {
      public static function wc_booking_complete_action11( $booking_id ) {
              if ( 'wc-booking-complete' !== current_action() ) {
                  return;
              }
              $booking = get_wc_booking( $booking_id );
              if ( 'complete' === $booking->get_status() ) {
                  $order_id = $booking->get_order_id();
                  static::maybe_complete_order($order_id);
              }
          }

      public static function maybe_complete_order( $order_id ) {
              $order = wc_get_order( $order_id );

              if ( $order->has_status( 'processing' ) ) {

                  $completed_bookings_order = null;
                  $booking_ids = WC_Booking_Data_Store::get_booking_ids_from_order_id( $order_id );
                  $count = count( $order->get_items() );

                  if ( $count > 0 && $count === count( $booking_ids ) ) {
                      foreach ( $booking_ids as $id ) {
                          $booking = get_wc_booking($id);
                          $completed_bookings_order = is_object($booking) ? 
                                  $booking->has_status('complete') : FALSE;

                          if ( ! $completed_bookings_order ) {
                              break;
                          }
                      }
                  }

                  if ( $completed_bookings_order ) {
                      $order->update_status('completed');
                      return 'completed';
                  }
              }

              return $order->get_status();
          }
      
      public static function maybe_complete_all_orders() {
        
        $processing_orders = wc_get_orders( array( 
            'status' => 'processing', 
            'return' => 'ids', 
            'posts_per_page' => -1 ) );
        
        foreach ( $processing_orders as $order_id ) {
            static::maybe_complete_order($order_id);
        }
    }
}

add_action( 'wc-booking-complete', array( MaraleAutocompleteOrders::class, 'wc_booking_complete_action11' ), 11, 1 );
//MaraleAutocompleteOrders::maybe_complete_all_orders();