Why is Netflix not working on iPhone 13 Pro Max?

Describe what you mean by “not working”. We’re not mind readers, just fellow users like yourself. Apple is not here in these forums. Are you using a browser like Safari to login to your Netflix account? Are you using the Netflix App on your phone? Are you sure you have the latest version of the Netflix App installed? Are you sure you are properly logged in to Netflix with your subscription credentials?

That would be an issue best taken up with Netflix Support.