I have the following example Turtle document:
@prefix dct: .
@prefix rdf: <
Apache Jena uses jsonld-java for JSON-LD input and output.
It is possible to setup the jsonld-java output as shown with:
https://jena.apache.org/documentation/io/rdf-output.html#json-ld ==> https://github.com/apache/jena/blob/master/jena-arq/src-examples/arq/examples/riot/Ex_WriteJsonLD.java
You'll need to consult jsonld-java as to whether the writer can do what you want.