[{"links":true,"loggedIn":true},{"booking":{"id":"3787847847","details":{"time":"2021-10-26 11:30:00.000Z","venue":"LHR Airport"},"results":[{"name":"ABC","loggedIn":true},{"name":"DEF","loggedIn":false}]}},{"booking":{"id":"000000000","details":{"time":"2021-10-29 12:29:00.000Z","venue":"Singapore Changi Airport"},"results":[{"name":"XYZ","loggedIn":true}]}}]

db.collection.aggregate([{"$unwind":{path:"$booking.results",includeArrayIndex:"arrayIndex"}}])