It is possible to create a json document in the event action and send it via the rest sender. Here an example where I call a rest service of the IFS system. But it will also work with an external URL:

Within the json you can use any variables of the event. But it is important to set additional header parameters. Otherwise you might run on an error:

Thanks @heibde  , is there any document showing step by step approach. i need an example for outbound where i will be writing to external system with api provided by them.