sitemap access

I’m redirecting every page from http:// or https:// to https://wwww.
That part works fine, but the only thing that doesn’t redirect is this link.

https://limousine.nl/sitemap_index.xml

That link gives me a white page, with just nothing on it.
Is it possible to redirect that link to

https://www.limousine.nl/sitemap_index.xml

I already tried something in the .htaccess,

RewriteEngine on
RewriteCond %{HTTPS} !=on [NC]
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}/$1 [R=301,L]

Do I need to do something extra or isn’t it even possible to redirect that link?

https://ww.wp.xz.cn/plugins/wordpress-seo/