Database
[{"_id":"d86d6b48-e949-4daa-8364-9ef008416ae8",users:[{name:"123"},{name:"222w"}]},{"key":2}]
Query
db.collection.aggregate([{"$match":{"_id":"d86d6b48-e949-4daa-8364-9ef008416ae8"}},{"$project":{"users":{"$slice":[{"$filter":{"input":"$users","as":"user","cond":{"$and":[{$eq:["$$user.name","123"]}]}}},0,100]}}},{"$project":{users:{"$size":"$users"}}}])