On the Post Page 404 tab, you can configure the major settings for the not found page.
What does a 404 page do?
The 404 page does two main things: It tells the visitor that they were successful in communicating with the web server, but the web server could not find the requested page. It prompts the visitor to go back to the working part of your website.
The default 404 page will appear like this in our theme: