[{"s_id":"618192d4654484639c47fa2d","clocked_out_at":"2021-11-05T10:00:00.000Z","clocked_in_at":"2021-11-05T03:00:00.000Z","visitor_id":"6166c10965959d147c69aa90"},{"s_id":"6182552fde30e84900ba33fd","clocked_out_at":"2021-11-05T11:00:00.000Z","clocked_in_at":"2021-11-05T04:00:00.000Z","visitor_id":"6182e4cea8b52121d01dff1b"},{"s_id":"6182552fde30e84900ba33fd","clocked_out_at":"2021-11-05T12:00:00.000Z","clocked_in_at":"2021-11-05T05:00:00.000Z","visitor_id":"6166c10965959d147c69aa90"},{"s_id":"6182552fde30e84900ba33fd","clocked_out_at":"2021-11-06T13:00:00.000Z","clocked_in_at":"2021-11-06T06:00:00.000Z","visitor_id":"6166c10965959d147c69aa90"}]

db.collection.aggregate([/** Convert to DateTime if not already*/{"$addFields":{"clocked_in_at":{"$toDate":"$clocked_in_at"},"clocked_out_at":{"$toDate":"$clocked_out_at"}}},{"$project":{"s_id":"$s_id","visitor_id":"$visitor_id","datetime":[{"day":{"$dateTrunc":{"date":"$clocked_in_at","unit":"day"}},"in":"$clocked_in_at"},{"day":{"$dateTrunc":{"date":"$clocked_out_at","unit":"day"}},"out":"$clocked_out_at"}]}},{"$unwind":"$datetime"},{"$group":{"_id":{"visitor_id":"$visitor_id","day":"$datetime.day"},"s_id":{"$first":"$s_id"},"clocked_in_at":{"$min":"$datetime.in"},"clocked_out_at":{"$max":"$datetime.out"}}},{"$project":{"_id":"$s_id","clocked_out_at":"$clocked_out_at","clocked_in_at":"$clocked_in_at","visitor_id":"$_id.visitor_id"}}])