Child Theme style.css changes aren’t showing. Parent “style-less.css” over rides it, and won’t update

You must enqueue your child theme’s stylesheet from the child theme’s functions.php file, as you would any other stylesheet. Specifying the parent theme’s stylesheet handle as a dependency is a good measure to ensure the proper load order.

function wpse406477_enqueue_child_styles() {
  wp_enqueue_style( 'mychild-style', get_stylesheet_uri(), [ 'parent-style' ] );
}

add_action( 'wp_enqueue_scripts', 'wpse406477_enqueue_child_styles' );

Note that compatibility with traditional mechanisms to override parent components from child themes varies from theme to theme. If your parent theme is not one of the default twenty* themes, you may need to refer to your theme’s documentation or inquire in the theme’s official support channels for the proper means to extend it with a child theme.