Is it possible to pass classes to twig include template
Yes @Clive, it's correct. I can simply declare a variable called &quot;card_classes&quot; and it is passed to the sub-template. During my tests I targeted an incorrect base template. It was my problem :-/
In the included template :
{% if card_classes is not defined %}
  {% set card_classes = [
    'card-view',
    'row',
    'row-cols-1',
    'row-cols-md-2',
    'row-cols-lg-3',
    ]
  %}
{% endif %}

{% if title %}
  &lt;h3&gt;{{ title }}&lt;/h3&gt;
{% endif %}
&lt;div{{ attributes.addClass(card_classes)}}&gt;
{% for row in rows %}
  {%
    set row_classes = [
      default_row_class ? 'views-row col',
    ]
  %}
  &lt;div{{ row.attributes.addClass(row_classes) }}&gt;
    {{ row.content }}
  &lt;/div&gt;
{% endfor %}
&lt;/div&gt;

By checking if card_classes variable is defined or not, I can set default classes in the included template itself, or override the default classes in the base template.
And now in base templates :
{# use default classes #}
{{ include('@my_theme/views/views-view-unformatted--card-template.html.twig') }}

or to override
{# override default classes by another set of classes #}
{%
  set card_classes = [
    'card-view',
    'row',
    'row-cols-1',
    'row-cols-md-2'
  ]
%}

{{ include('@my_theme/views/views-view-unformatted--card-template.html.twig') }}