Getting only the insides of the source from the elastic search query

What im trying to do is to get only the source from the elastic search query in order to skip the processing on the javascript, so i could squize some more performance gains.Is it possible to do so?

So here is what i currenly do, i just get the data from the elastic search and iterate every one of those objects in order to construct an array that only contains the what’s inside of _source:

const { body } = await this.elsticSearchService.search<any>({
 index: this.configService.get('ELASTICSEARCH_INDEX'),
 body: {
 query: {
    match_all: {},
    },
    size: 10000,
  },
});

const hits = body.hits.hits;

return hits.map((item: any) => item._source);

So my question is, is there a way to only get the _source from the elastic search, in order
to skip the processing on the JavaScript?
So the object returned from the elastic search would look like this

[
0:{ "key": "value"}, // key,value from _source object
1:{ "key": "value"}, // key,value from _source object
2:{ "key": "value"}, // key,value from _source object
]

so without all of the other fields like hits, took etc…