Response body: Payload Too Large - node.js

Question

I am writing a POST request to a mock api that will store a file and its binary. The error I'm receiving is:
<Buffer 49 44 33 03 00 00 00 00 01 10 54 49 54 32 00 00 00 0b 00 00 00 61 6c 61 72 6d 53 6f 75 6e 64 54 58 58 58 00 00 00 17 00 00 00 53 6f 66 74 77 61 72 65 ... 115969 more bytes>
Error: SyntaxError: Unexpected token P in JSON at position 0
at JSON.parse (<anonymous>)
at safeParseJSON (C:\Users\Student\Downloads\RequestMaker\fetchTest.js:36:19)
at processTicksAndRejections (internal/process/task_queues.js:93:5)
at async C:\Users\Student\Downloads\RequestMaker\fetchTest.js:72:5
Response body: Payload Too Large
const fs = require('fs');
const fetch = require('node-fetch');
async function makePostReq(time, date) {
let file = 'sound.mp3'
fs.readFile(file, 'utf8', async (err, data) => {
if (err) {
console.error(err)
return
}
let buf = Buffer.from(data, 'utf8');
console.log(buf)
let body = {
"File Name": "sound.mp3",
"Binary": buf
}
let url = 'https://6050ffd85346090017671094.mockapi.io/posts/mockData'
await fetch(url, {
method: 'POST',
body: JSON.stringify(body),
headers: { 'Content-Type': 'application/json' },
})
.then(safeParseJSON)
.then(json => console.log(json));
})
}
async function safeParseJSON(response) {
const body = await response.text();
try {
return JSON.parse(body);
} catch (err) {
console.error("Error:", err);
console.error("Response body:", body);
}
}
A lot of the solutions online talk about limiting the size using express. I'm only using Nodejs to do this because it's going to be part of an Alexa Skill once it works, so express won't work. Are there any ideas on how I can send the binary of a file as a POST request?
Thank you.