Add checkbox in node menu settings I would like to add one checkbox in Menu settings at node /node/add/{Content types}

I am not sure how to do that.
I need to use Form and Controller. 

What form I need to include? This is some of them.

use Drupal\Core\Form\ConfigFormBase;
use Drupal\Core\Form\FormStateInterface;


And after I need to implemente Implements hook_form_FORM_ID_alter().

Is my thinking ok?
If I understand you correct, you want a menu to appear only at a certain content type? It is not done from there.

In Drupal 8 each menu is a block; After you have created the menu regularly with the native API unchanged, just add the block to the desired region and then set that block to appear only in a certain region you want it to appear in (You should see such an option in the block's conf page).