Database

[{"_id":"60753fd9b249ad0dfa1eeb48","name":"Random Name 1","email":"randomname1@zmel.kom","likings":[{"breakfast":{"eat":"oats","drink":"milk"}},{"lunch":{"eat":"beef","drink":"pepsi"}},{"dinner":{"eat":"steak","drink":"champagne"}}]},{"_id":"60753fd9b249ad0dfa1eeb58","name":"Random Name 2","email":"randomname2@zmel.kom","likings":[{"breakfast":{"eat":"cereals","drink":"coffee"}},{"lunch":{"eat":"salad","drink":"hot-water"}},{"dinner":{"eat":"biryani","drink":"apple juice"}}]}]

Query

db.collection.update({"name":"Random Name 2","likings.dinner":{"$exists":true}},{"$set":{"likings.$.dinner.drink":"PEPSI"}})

Result