Change the Paragraph Block's Placeholder Text

block-editor-change-paragraph-placeholder-text.php

<?php
/**
 * Plugin Name:       DLX Change Paragraph Placeholder
 * Plugin URI:        https://dlxplugins.com
 * Description:       Change the placeholder text for the paragraph block.
 * Version:           1.0.0
 * Requires at least: 6.0
 * Requires PHP:      7.3
 * Author:            Ronald Huereca
 * Author URI:        https://mediaron.com
 * License:           GPL v2 or later
 * License URI:       https://www.gnu.org/licenses/gpl-2.0.html
 *
 * @package DLXChangeParagraphPlaceholder
 */

namespace DLXPlugins\ChangeParagraphPlaceholder;

add_filter( 'block_type_metadata', __NAMESPACE__ . '\modify_paragraph_attributes', 10, 1 );

/**
 * Set Paragraph defaults.
 *
 * @param array $metadata {
 *    An array of arguments.
 *
 *    @type string $name       Block name.
 *    @type array  $attributes Block attributes.
 * }
 */
function modify_paragraph_attributes( $metadata ) {
	// Check the block type.
	if ( 'core/paragraph' !== $metadata['name'] ) {
		return $metadata;
	}

	// Add accordion view (collapsed view).
	$metadata['attributes']['placeholder']['default'] = 'Please type or use "/" command.';

	// Return the metadata.
	return $metadata;
}