Call the /token endpoint as a POST.
You need the code that Oauth adds as a response parameter in the redirect uri, client id, scopes, redirect uri, and client secret.
import requests, json
code = "XXXX"
scopes = ['user']
redirect_uri = "url"
client_id = 0000000000
client_secret = "XXXX"
url = "https://replit-oauth.coolcodersj.repl.co/token"
response = requests.post(url, data=json.dumps({
"code": code,
"scopes": "+".join(scopes),
"clientid": client_id,
"clientsecret": client_secret,
"redirect_uri": redirect_uri
}))
token = response.text