Database
[{"_id":{"$oid":"60a3f7d0f988f1e57212a81e"},"user_id":"609d22188ea8aebac56f9dc3","__v":{"$numberInt":"0"},"words":[{"word_id":"609d1bba887035b9cd4292aa","last_practiced":"2021-05-15 16:00:00","strength":{"$numberInt":"1"}},{"word_id":"609d1c35861d99b9effc0027","last_practiced":"2021-05-15 16:00:00","strength":{"$numberInt":"1"}},{"word_id":"609d1dcbc99e8dba538208d7","last_practiced":"2021-05-15 16:00:00","strength":{"$numberInt":"1"}}]}]
Query
db.collection.aggregate([{$match:{"user_id":"609d22188ea8aebac56f9dc3","words.word_id":{$in:["609d1cfe0806daba1b0502bf","609d1bba887035b9cd4292aa"]}}},{$addFields:{words:{$filter:{input:"$words",cond:{$in:["$$this.word_id",["609d1cfe0806daba1b0502bf","609d1bba887035b9cd4292aa"]]}}}}}])