Database

[{title:"a",articles:[{article_dt:"2023-05-09T00:00:00.000+00:00",seq:1},{article_dt:"2021-12-31T00:00:00.000+00:00",seq:2},{article_dt:"2022-12-30T00:00:00.000+00:00",seq:3}]}]

Query

db.collection.aggregate([{$project:{articles:{$filter:{input:"$articles",as:"art",cond:{$lt:["$$art.article_dt","2023-01-01T00:00:00.000+00:00"]}}}}},{"$unwind":"$articles"},{"$sort":{"articles.article_dt":1}},{"$group":{"_id":"$_id","articles":{"$push":{article_dt:"$articles.article_dt",seq:"$articles.seq"}}}}])

Result