Alternate Website with Different Plugins

You should replicate your content onto a local installation of WordPress.
https://codex.ww.wp.xz.cn/Installing_WordPress#Installing_WordPress_on_your_own_Computer
https://make.ww.wp.xz.cn/core/handbook/tutorials/installing-a-local-server/

If you don’t like that, you can create a folder on your site and install a new copy of WordPress there, set it so the search engines ignore it, and load your content in there. When you have it all ready for going live, it is a simple matter to tell WordPress to control the root instead of just the folder. Of course, you delete the original and make a small change to the new one, and it’s live.
https://codex.ww.wp.xz.cn/Giving_WordPress_Its_Own_Directory