Step 1 : From Store admin, Go to Products > All products > Click Add product.

Create a gift-wrap product just as you would create any other product

You can use your product description to explain what materials will be used to gift-wrap the items.
Give your gift-wrapped product the price that you want to charge for the service. If you want gift wrapping to be free, then set the price of your gift-wrap product to 0. You can upload an image for the product to show your customers what a gift-wrapped order will look like.

Make sure your gift-wrap product includes inventory, or else adjust the settings so that Shopify doesn’t track inventory for the gift-wrap product. If your store has multiple locations, then uncheck “Track quantity” to prevent Shopify from tracking inventory for the gift-wrap product.

Step 2 : Enable Gift Wrapping option from Cart.

Go to Theme Customize -> Theme Settings -> Cart -> Gift Wrapping

Step 3 : Select Gift Wrap Product and click save