Database
[{engagement:{loves:["5e87a316457e874ce886356c","5e87a316457e874ce886356d","5e87a316457e874ce886356e","5e87a316457e874ce886356f"],loveCount:4,},_id:"5e87c097c9374e6628a499b"}]
Query
db.collection.aggregate([{$addFields:{"engagement.loves":{$filter:{input:"$engagement.loves",cond:{$eq:["$$this","5e87a316457e874ce886356d"]}}}}}])