The developer can extend the existing CartltemPrices GraphQL schema to include a custom base_price field by adding the following code to the module’s etc/schema.graphqls file:

extend type CartltemPrices { base_price: Money! @doc(description: “The base price of the cart item”) }

This code adds a new field called base_price to the CartltemPrices type and specifies that it is of type Money and it is not nullable. The @doc directive adds a description for the field that will be shown in the schema documentation. The developer also needs to create a custom resolver class for the base_price field and declare it in the di.xml file of the module. Verified References: [Magento 2.4 DevDocs] [Magento Stack Exchange]