Style H4 in editor

Hi. Could you kindly assist me with the correct code to style the h4 in the editor using the$css code below just below the first one? I want it to have font-size:21px; text-transform:capitalize; font-weight:600;

add_action( 'enqueue_block_editor_assets', function() {
    $css .= '.editor-block-list__block a, .editor-block-list__block a:visited {color: #000;}';
    wp_add_inline_style( 'generate-block-editor-styles', $css );
}, 100 );

Thank you.