How to make products available automatically as soon as the pre-order period ends

By default, all products and categories are set as (Global pre-order stock status), so it can be managed from pre-order settings.

You can choose if the product should be set as In Stock / Out of stock on the pre-order date

To make your product available you should set as In Stock

Check full documentation for Pre-orders for Woocommerce

How to prevent new orders after the pre-order date arrives?>