split field elements in 'prefix', 'content' and 'suffix'

Here's a field template that makes the job:

{%
  set classes = [
    'field',
    'field--name-' ~ field_name|clean_class,
    'field--type-' ~ field_type|clean_class,
    'field--label-' ~ label_display,
  ]
%}
{%
  set title_classes = [
    'field__label',
    label_display == 'visually_hidden' ? 'visually-hidden' : '',
  ]
%}

{# get prefix and suffix #}
{% set prefix = element['#items'].getFieldDefinition().getSetting('prefix') ?? '' %}
{% set suffix = element['#items'].getFieldDefinition().getSetting('suffix') ?? '' %}

{# display the field #}
<div{{ attributes.addClass(classes) }}>
  <div{{ title_attributes.addClass(title_classes) }}>{{ element['#title'] }}</div>
  {% if multiple %}
    <div class='field__items'>
  {% endif %}
  {% for item in items %}
    <span>{{ prefix }} </span>
    <span{{ item.attributes.addClass('field__item') }}>{{ item.content }}</span>
    <span> {{ suffix }}</span>
  {% endfor %}
  {% if multiple %}
    </div>
  {% endif %}
</div>

The use case is kind of narrow. Only a few field types have support for prefix and suffix. Anyway I think it's a case for Twig Field Value → module as it seems more related to processing field values.

I guess it could be filters like this.

{{ content.field_name|field_prefix }}
{{ content.field_name|field_suffix }}