How do I theme exposed filters?
This is not possible in a Views template. Form elements rendered here can't be submitted because they are not in a html form (between &lt;form&gt;/&lt;/form&gt;).

You need a custom form template so that you are inside of the form. For the Views exposed form there is already a customizable form template in core:

/core/themes/stable/templates/views/views-exposed-form.html.twig

{#
/**
 * @file
 * Theme override of a views exposed form.
 *
 * Available variables:
 * - form: A render element representing the form.
 *
 * @see template_preprocess_views_exposed_form()
 */
#}
{% if q is not empty %}
  {#
    This ensures that, if clean URLs are off, the 'q' is added first,
    as a hidden form element, so that it shows up first in the POST URL.
  #}
{{ q }}
{% endif %}
{{ form }}


You can copy this twig to the /template folder of your theme and start theming the form elements:

  {{ form.field_category_target_id }}
  {{ form.field_address_locality }}
  {{ form|without('field_category_target_id', 'field_address_locality') }}




See How do I assign a template to the user edit form? for more info how to add and use these form templates in other forms.