Missing formatter options for field from a custom table defined in hook_views_data() I integrated a custom database table to views using hook_views_data().
$data['custom_watchdog']['message'] = [
    'title' =&gt; 'Message',
    'help' =&gt; 'Full log message.',
    'field' =&gt; [
        'id' =&gt; 'standard',
    ],
    'filter' =&gt; [
        'id' =&gt; 'string',
    ],
];

It works, as I can display values in a view, but it misses a formatter option.
For example, the Taxonomy term: Description field has formatter options which allows to select Default or Trimmed.
Why isn't it available for my custom field?
You are comparing a standard Views field with an entity field. Only entity fields have field formatters. Create a custom entity instead of a custom table if you want to use this feature. For a standard field you have to use the options provided by Views. There is a trim option as well, but it is named differently, trim in the alter section. You see it in Views UI. Try to configure it and check the exported View.