Step 2: Go to the Settings module > Catalog Settings.
Step 3: Under Product detail related settings, select the check box for Delivery Information.
Step 4: Immediately after that, two text boxes are displayed allowing you to define the in-stock and out-of-stock messages. Define the messages. If you leave these text boxes blank, no delivery information will be shown.
Below are the rules to display the messages:
In-stock message: Display this message when the product is in stock.
Out-of-stock message: Display this message when the product is out of stock and/or your store allows backorders.
Step 5: Click Save Changes at the top right of the screen to confirm the change. Below is how the delivery information looks on mobile app.