How to start session globally?

I looked at the documentation, https://bcit-ci.github.io/CodeIgniter4/l...-a-session, which says,

Code:

To access and initialize the session:

$session = \Config\Services::session($config);

Am I supposed to put this code in the constructor of every Controller class where I need to manipulate session data?

I found that I can also use start session using this helper

Code:

session()->start();

but again I need to declare that in all files before I can use session.

I need to know the same for db and custom common functions helper file.

$db = \Config\Database::connect();

All I am trying to find out if I should be placing these in a common file? Or perhaps, declaring in each file is the suggested practice???