craftql | A CLI tool to visualize GraphQL schemas and to output a graph data structure as a graphviz .dot form

As the documentation states, using possibleTypes is only possible if using apollo-client version 3.0 or higher, which is currently in beta. Unless you're using the @apollo/client package as shown here, passing in the possibleTypes parameter will do nothing.

Additionally, you need to make sure each property in the object you pass in is the name of a union or interface, not the name of a field. From the docs

You can pass a possibleTypes option to the InMemoryCache constructor to specify supertype-subtype relationships in your schema. This object maps the name of an interface or union type (the supertype) to the types that implement or belong to it (the subtypes).

In other words, instead of using contentEngine as the key, you would use whatever the name of type of the contentEngine field was.

If you're using an earlier version of apollo-client, you'll need to create an IntrospectionFragmentMatcher as outlined in the docs here.