Fable 5 (paid)

<?php

declare(strict_types=1);

namespace Drupal\current_date\Plugin\Block;

use Drupal\Core\Block\Attribute\Block;
use Drupal\Core\Block\BlockBase;
use Drupal\Core\Datetime\DrupalDateTime;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;

/**
 * Provides a block that displays the current date.
 */
#[Block(
  id: 'current_date_block',
  admin_label: new TranslatableMarkup('Current date'),
  category: new TranslatableMarkup('Custom'),
)]
final class CurrentDateBlock extends BlockBase {

  /**
   * {@inheritdoc}
   */
  public function defaultConfiguration(): array {
    return [
      'date_format' => 'd.m.Y',
    ] + parent::defaultConfiguration();
  }

  /**
   * {@inheritdoc}
   */
  public function blockForm($form, FormStateInterface $form_state): array {
    $form['date_format'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Date format'),
      '#description' => $this->t('A PHP date format string. Example: %example.', [
        '%example' => 'd.m.Y H:i',
      ]),
      '#default_value' => $this->configuration['date_format'],
      '#required' => TRUE,
    ];

    return $form;
  }

  /**
   * {@inheritdoc}
   */
  public function blockSubmit($form, FormStateInterface $form_state): void {
    $this->configuration['date_format'] = $form_state->getValue('date_format');
  }

  /**
   * {@inheritdoc}
   */
  public function build(): array {
    $formatted = (new DrupalDateTime('now'))->format($this->configuration['date_format']);

    return [
      '#markup' => $formatted,
      '#cache' => [
        'max-age' => 0,
      ],
    ];
  }

}