I want to see 404 pages of browser standard

■Environment
I'm building a site on wordpress, but except for the URL created for membership only
I'd like to see 404 pages that my browser spouts as a standard.

■ What I tried
If you write the following in the template,

<?php
/*
Template Name:test
*/
header("HTTP/1.1404 Not Found");
?>

The page appears white.

<?php
/*
Template Name:test
*/
?>

It will be displayed as white here as well.

Delete 404.php and delete browser cache
I tried to display it, but the page 404.php appears.
(Is there a cache left on the browser side or is it being processed by the wordpress core?)
Are Google caches displayed?)

There are many ways to create the original 404 page, but
I couldn't find a way to intentionally display the 404 that the browser spouts normally.

ブラウザThe 404 that the browser spouts as a standard is
When accessing URLs that do not exist in IE and Chrome
The display of 404 is different, but it is the 404 page of the original.

Is php possible if we want to do this?
Or do I need to set it up in apache?