Database
[{"_id":ObjectId("649f51ecd531d6b037117e77"),"voucherNumber":"ABC12345"},{"_id":ObjectId("649f51ecd531d6b037117e78"),"voucherNumber":"ABC12346"},{"_id":ObjectId("649f51ecd531d6b037117e79"),"voucherNumber":"ABD12347"},{"_id":ObjectId("649f51ecd531d6b037117e7a"),"voucherNumber":"ABD12348"},{"_id":ObjectId("649f51ecd531d6b037117e7b"),"voucherNumber":"ABE12349"},{"_id":ObjectId("649f51ecd531d6b037117e7c"),"voucherNumber":"ABCF12350"}]
Query
db.collection.aggregate([{$match:{$expr:{$in:[{$substrCP:["$voucherNumber",0,3]},["ABC","ABF"]]}}}])