Database
[{time:1649083392,volume:"20384.28",open:444.42,close:444.56,high:444.76,low:444.36},{time:1649083448,volume:"20384.28",open:444.42,close:444.56,high:444.76,low:444.36},{time:1649083501,volume:"20384.28",open:444.42,close:444.56,high:444.76,low:444.36},{time:1650083501,volume:"20384.28",open:444.42,close:444.56,high:444.76,low:444.36}]
Query
db.collection.aggregate([{$sort:{time:-1}},{$group:{_id:{$dateTrunc:{date:{$toDate:{$multiply:["$time",1000]}},unit:"day"}},volume:{$sum:{$toDecimal:"$volume"}},lastItem:{$first:"$$ROOT"}}}])