Custom Search Results Page

You need to correctly override the page you want them not to see.
So for example, if you have a portfolio page that looks one way, you can override that by having a custom portfolio.php of your own.

In there you can modify the look, but also you can setup your custom query that will basically override the search to show what you want to show.

There is not really anyway to do it without editing any PHP files, but to avoid losing changes I would suggest putting your new templates in a child theme or plugin.

This might help you with the templates available and how they are used.
https://developer.wordpress.org/themes/basics/template-hierarchy/