db={"users":[{"_id":1,},{"_id":5,},{"_id":14,},{"_id":15,},],"follows":[{"_id":10,"follower":1,"followee":5},{"_id":11,"follower":1,"followee":14}]}

db.users.aggregate([{$addFields:{sortBy:{$cond:{if:{$in:["$_id",[5,14]]},then:0,else:1}}}},{$sort:{sortBy:1}},{$unset:"sortBy"}])