In a WordPress block-based theme, use has_block() to check if the home template, homepage, or front-page includes a certain block.

home-page-has-block.php

<?php
if ( wp_is_block_theme() && is_front_page() ) {
	$block_template = get_block_templates( [ 'slug__in' => [ 'home' ] ] );
	$block_content  = isset( $block_template[0] ) ? $block_template[0]->content : '';

	$home_has_block = has_block( 'my/block', $block_content );
}