Rich text editor (RTE) 

The RTE is by default supplied by the system extension typo3/cms-rte-ckeditor . See also the according chapter in TYPO3 explained.

In TCA a RTE is a normal text field with the option enableRichtext enabled.

Examples for Rich text editor fields in the TYPO3 Backend 

RTE with minimal configuration 

The biography of a speaker with the minimal configuration

The biography of a speaker with the minimal configuration

EXT:my_extension/Configuration/TCA/Overrides/330-tx_myextension_speaker-bio.php
<?php

use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;

defined('TYPO3') or die();

ExtensionManagementUtility::addTCAcolumns('tx_myextension_speaker', [
  'bio' => [
    'label' => 'my_extension.db:speaker.bio',
    'config' => [
      'type' => 'text',
      'enableRichtext' => true,
      'richtextConfiguration' => 'minimal',
    ],
  ],
]);
ExtensionManagementUtility::addToAllTCAtypes(
  'tx_myextension_speaker',
  'bio',
  '',
  'before:--div--;my_extension.db:tab.integration',
);
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RTE with full configuration 

EXT:my_extension/Configuration/TCA/Overrides/130-tx_myextension_conference-description.php
       'enableRichtext' => true,
+      'richtextConfiguration' => 'full',
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RTE with default configuration 

The description of a conference

The description of a conference

EXT:my_extension/Configuration/TCA/Overrides/130-tx_myextension_conference-description.php
<?php

use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;

defined('TYPO3') or die();

ExtensionManagementUtility::addTCAcolumns('tx_myextension_conference', [
  'description' => [
    'label' => 'my_extension.db:conference.description',
    'l10n_mode' => 'prefixLangTitle',
    'config' => [
      'type' => 'text',
      'enableRichtext' => true,
    ],
  ],
]);
ExtensionManagementUtility::addToAllTCAtypes(
  'tx_myextension_conference',
  'description',
  '',
  'before:--div--;core.form.tabs:categories',
);
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Properties of the TCA column type text with enabled rich text 

Almost all properties of field type text are available.