Add additional block styles from your child theme: https://silvanhagen.com/writing/additional-block-styles-child-theme

functions.php

<?php

namespace OllieChild;

function enqueue_custom_child_block_styles() {

    // Scan our styles folder to locate block styles.
    $files = glob( get_stylesheet_directory() . '/assets/blocks/*.css' );

    foreach ( $files as $file ) {

        // Get the filename and core block name.
        $filename   = basename( $file, '.css' );
        $block_name = str_replace( 'core-', 'core/', $filename );

        wp_enqueue_block_style(
            $block_name,
            array(
                'handle' => "ollie-child-block-{$filename}",
                'src'    => get_theme_file_uri( "assets/blocks/{$filename}.css" ),
                'path'   => get_theme_file_path( "assets/blocks/{$filename}.css" ),
            )
        );
    }
}
add_action( 'init', __NAMESPACE__ . '\enqueue_custom_child_block_styles', 20 );