Express receiving string instead of boolean

This question has been asked before but the question did not address the sending method and the solution marked does not work for me.

I am trying to get a boolean in a JSON object on the back end but I get a string instead.

I am sending an array of objects from axios with this:

const data = [{
  clientName: 'A client',
  columns: [{ 
    name: 'Keywords', 
    options: [{
      keyword: false,
      include: true
    }] 
  }]
}]

await axios.post('/config', { data })

But when I try to see what type are the options I get strings instead of booleans

On the back end I have this

server.js

import express from 'express'
import cors from 'cors'
import config from './routes/config.js'

const prod = process.env.NODE_ENV === 'production'
const app = express()

// Middleware
app.use(cors())
app.use(express.json())
app.use(express.urlencoded({ extended: true }))
app.use(express.static('uploads'))

app.use('/config', config)


// Start
const port = process.env.PORT || prod ? 5002 : 4003
app.listen(port, () => console.log(`Listening on port ${port}.`))

And the route

config.js

import { Router } from 'express'
import { writeFile } from 'fs/promises'


router.post('/config', async (req, res) => {
  const { data } = req.body.data

  // I want to write the data array with all of its objects however many they are, to file
  await writeFile(config.json, JSON.stringify(data)) 


  console.log(data)
}

export default router

[{
  clientName: 'A client',
  columns: [{ 
    name: 'Keywords', 
    options: [{
      keyword: 'false', // <-- string
      include: 'true'   // <-- string
    }] 
  }]
}]

############## UPDATE

My bad, I thought the react front end was sending booleans, it turns out they were actually strings

<option value={true}>Keyword</option>
<option value={false}>Domain</option>