Citing: https://jsonapi.org/format/#fetching-sparse-fieldsets

A client MAY request that an endpoint return only specific fields in the response on a per-type basis by including a fields[TYPE] parameter.

The value of the fields parameter MUST be a comma-separated (U+002C COMMA, “,”) list that refers to the name(s) of the fields to be returned. An empty value indicates that no fields should be returned.

If a client requests a restricted set of fields for a given resource type, an endpoint MUST NOT include additional fields in resource objects of that type in its response.

If a client does not specify the set of fields for a given resource type, the server MAY send all fields, a subset of fields, or no fields for that resource type.

GET /articles?include=author&fields[articles]=title,body&fields[people]=name HTTP/1.1 Accept: application/vnd.api+json

Examples: https://jsonapi.org/examples/