Randomize text content in heading block

functions.php

<?php

\add_filter( 'render_block_core/heading', __NAMESPACE__ . '\\randomize_h1_heading_block_on_front_page', 10, 2 );
/**
 * Randomizes content of H1 heading blocks on the front page.
 *
 * @since 1.0.0
 *
 * @param string $content Block HTML content.
 * @param array  $block   Block data.
 *
 * @return string
 */
function randomize_h1_heading_block_on_front_page( string $content, array $block ): string {
	$page_condition = \is_front_page();
	$heading_level  = $block['attrs']['level'] ?? null;

	if ( $page_condition && $heading_level === 1 ) {
		$strings = [
			'Random title one',
			'Another random title',
			'Third random title',
		];

		$content = \str_replace(
			\trim( \strip_tags( $content ) ),
			$strings[ \array_rand( $strings ) ],
			$content
		);
	}

	return $content;
}