Hi. It's not so easy and depends on your template. You will need to edit the viewport meta tag to fixed width in your template's index.php. Remove everything grid related from bootstrap.css (if your template uses bootstrap) and some additional css coding.

Hello ธัญญะ วรรธนพิเชฐ

Exactly what Pavel said. You need to remove meta tag viewport and media query css. If you are talking about SP Page Builder pages, then just set it for the desktop view and ignore other views. Surely, it will be a lot of work.

Best regards