Robots.txt for a multilanguage site where root is redirected

I have a site which offers two languages, English and Spanish. When the user navigates to the home page, let’s say www.example.com the page redirects you to either /es if your browser language is Spanish or English otherwise.

At the moment the robots.txt I have is:

User-agent: * Allow: /  Sitemap: https://www.example.com/sitemap_index.xml 

because I’m defining all hreflang alternate URLs in the sitemap_languages.xml and all URLs are listed also in the sitemap.xml. My question is more towards the configuration of the robots.txt because I’m not sure if I should be allowing any user agent to crawl the / page. As that page always redirects to the home of either /en or /es I believe that should be disallowed.

Should I then do:

User-agent: * Disallow: / Allow: /es Allow: /en  Sitemap: https://www.example.com/sitemap_index.xml 

I’m not sure if that could cause a crawl issue or whether there is another way to achieve the same result.