I believe that you are looking for the private metafield: https://shopify.dev/tutorials/store-data-in-metafields#private-metafields
When you conduct a service-based business using the Shopify store, you may require a booking system. This will help you maintain when customers may appear at your store. Many niches may want this. For example, restaurants, barbers, holiday rentals, and more. Using one of the Shopify booking system applications makes the process easier and more effective for the customer. This saves you a lot of time as well.
If you need any further guidance, we will be happy to serve you. Please email us and we will connect with you shortly.