Database
db={"Model":[{_id:ObjectId("5a934e000102030405000001"),"field":12}],"AnotherModel":[{"someField":ObjectId("5a934e000102030405000001"),show:true},{"someField":ObjectId("5a934e000102030405000001"),show:false}]}
Query
db.Model.aggregate([{$project:{field:1}},{$lookup:{from:"AnotherModel",let:{id:"$_id"},pipeline:[{$match:{show:true,$expr:{$eq:["$someField","$$id"]}}}],as:"field"}},{$unwind:{path:"$_id"}}])