Can PHP handle a GraphQL object with an unknown field?

let’s say I have a resource product with fields like

• id
• name
• description
• externalSettings

and external settings is JSON field with unknown data, it can be any data set by the merchant, how can I describe it???

type Product {
   id: ID!,
   name: String!,
   description: String!,
   externalSettings ??? 
}

which type should be here, it’s a JSON object but I can’t describe internals as I do not know them, I just want to be able to query that json as whole and that’s it