How do I send .pem certificate in an axios request?

Question

I'm trying to convert the following python code into javascript form so I can send the client-2048 files to the server, does anyone know how I would do this. I don't know any python and I'm struggling to find out online how I would include the username, password, headers and client-2048 files in my axios request.

import requests
 
#openssl x509 -x509toreq -in certificate.crt -out CSR.csr -signkey privateKey.key
 
 
payload = 'username=myusername&password=password'
headers = {'X-Application': 'SomeKey', 'Content-Type': 'application/x-www-form-urlencoded'}
 
resp = requests.post('https://identitysso-cert.betfair.com/api/certlogin', data=payload, cert=('client-2048.crt', 'client-2048.key'), headers=headers)

This is what I have so far, where would I include the 2048 files in this post request?

const login_endpoint = 'https://identitysso-cert.betfair.com/api/certlogin'
        
        const login_res = await axios.post(login_endpoint, {
            username: 'username',
            password: 'password'
        }, {
            headers: {
                'Accept': 'application/json',
                'X-Application' : 'app_key',
                'Content-Type': 'application/x-www-form-urlencoded'
            }
        })