You can sell products that are out of stock or unavailable by setting them up as pre-orders. You can use pre-orders to help you forecast the demand for a new product that you're releasing or to create customer excitement around a new release.
To create a product "Pre-order," we have provided an option "Continue selling when out of stock" in the settings of the product variants. In the video below, we show you 2 ways:
Pre-order option for each variant
Pre-order option for all variants