Array in .env file

I was hoping from the docs here: Treating Environment Variables as Arrays that I could access something in the .env file that used dot syntax as an array but it doesn't seem to work.[url=https://codeigniter4.github.io/userguide/general/configuration.html#treating-environment-variables-as-arrays][/url]
Here is an example, after copying the env file to .env and uncommenting the database.default section:

PHP Code:

$database = getenv('database');
var_dump($database); 


$database just contains boolean false.

Is it possible to access everything prefixed with e.g. 'database' as an array?
Thanks.