An external system integrates functionality of a product catalog search using Adobe Commerce GraphQL API.

According to the Adobe Commerce documentation, to extend an existing GraphQL interface, the keyword extend must be used before the interface name. This indicates that the new declaration is adding or modifying fields to the existing interface, rather than redefining it. If the keyword extend is omitted, the new declaration will be ignored and the original interface will be used. In this case, the Architect wants to change the type of the my_attribute field in the ProductInterface interface, which is already declared in the Magento.CatalogGraphQl module. Therefore, the Architect should use the keyword extend before declaring the ProductInterface interface in the schema.graphqlsfile of the custom module. This will allow the Architect to override the type of the my_attribute field from Int to MyAttributeType.

References:

Extend existing schema | Adobe Commerce Developer Guide

Schema language with GraphQL | Adobe Commerce