Database
[{_id:ObjectId("5a934e000102030405000000"),date:ISODate("2020-05-05T00:00:00.000Z"),counter:1},{_id:ObjectId("11934e000102030405000111"),date:ISODate("2020-04-01T00:00:00.000Z"),counter:2}]
Query
db.collection.aggregate([{$match:{_id:ObjectId("5a934e000102030405000000")}},{$addFields:{date:ISODate("2020-05-06T00:00:00.000Z"),counter:{$cond:[{$eq:["$date",ISODate("2020-05-06T00:00:00.000Z")]},{$add:["$counter",1]},0]}}}])