lowdb change format database (SET)(PUSH)

Question

I have this form look below

{
  "options": {
    "valueone": {
      "test": "okay"
    },
   "valuetwo": {
     "test": "okay"
}
  }
}

const low = require('lowdb')
const FileSync = require('lowdb/adapters/FileSync')
 
const adapter = new FileSync('db.json')
const db = low(adapter)
 
const options = 'valueone' // or "valuetwo"
db.defaults({ options: {} })
  .write()
 db.set("options", {[options]: { test: 'okay'}}).write()

I don't know how to rewrite to (PUSH) instead of (SET) because set updates or writes. and I need to add with exactly the same format. Friends, I can't do it anymore. https://www.npmjs.com/package/lowdb/v/2.0.0