Database connection

Can any one please explain my bellow queries?
If writing two MySql queries in a single model method then, will CI 3.x or CI 4.x make two database connections for each query?
How database connection works in CI 3.x from controller to model or view?
When database connection opens and when closes in CI 3.x  or CI 4.x?

CodeIgniter 4 User Guide - Connecting to your Database

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )