Add top level menu active menu class to child pages without adding submenu level in admin panel

additional_active_item_classes.php

<?php

function additional_active_item_classes( $classes = array(), $menu_item = false ) {
    // custom taxonomy
    if ( $menu_item->title == 'Custom Tax Name Page' && is_tax('custom_tax') ) {
        $classes[] = 'current-menu-item';
    }
    // custom post type single
    if ( $menu_item->title == 'Custom Post Type Page' && is_singular('products') ) {
        $classes[] = 'current-menu-item';
    }
    // blog post single
    if ( $menu_item->title == 'Blog Page' && is_singular('post') ) {
        $classes[] = 'current-menu-item';
    }
    return $classes;
}
add_filter( 'nav_menu_css_class', 'additional_active_item_classes', 10, 2 );