How to customize a node--type.html.twig template? I activated the devel and devel kint modules. I also activated twig debugging, so, I can know which are templates used by Drupal.

So, I created a content-type named album that contains a field named tracks.

Now, I want customize this content type, so I created node--album.html.twig in templates folder of bartik, which works so I can begin to customize this template.

Now, I have to know which are variables used by this template. In comment section of node--album.html.twig I can read that content variable can be used to display content of page. I also read I can use subset of content, such as content.field_example to display a field.

OK, so if I want to modify rendering of field_tracks I can use content.field_tracks. Before using this variable I wanted to know all content variable, so I've written [[ kint(content) ]] in content section of this file. I rebuilt the cache, and I seen that content is an array, not an object as suggested in comment section of node file.

So, if I print [[ content.field_tracks ]] it returns nothing.

If I use kinkt() without parameters it breaks drupal and point me to core/install.php.

The same as I use d() without parameters.

At this point I am confused: there is a way to modify node--type twig templates without creating a file for each field?
Here is some examples 

Render the whole field markup

{{ content.field_text }}


Get just the value of the field

{{ content.field_text.value }}


Get a field value from authors object

{{node.uid.entity.field_gender.value}}


For field above you can get the machine name of the field as you see it for example in admin/structure/types/manage/page/fields

For multivalue fields look at some examples here 

Read more about how to find more variables here