The best approach is to:

1. Take a backup of your site. There are few good free plugins out there like : All-in-One WP Migration and Duplicator.

2. Install the site on your local computer. You will need to install XAMP/LAMP or WAMP based on your operating system.

https://www.wpbeginner.com/wp-tutorials/how-to-move-live-wordpress-site-to-local-server/

3. Make all the changes you want on the localhost.

4. Once done, take a backup again but this time of localhost an push it to the live server.

https://premium.wpmudev.org/blog/guide-to-migrating-localhost-wordpress-to-live-site/

I hope it answers your question.

Hi Kyrstan,

As Pramod mentioned, you can set up a local version for development, but if that proves too daunting, or doesn’t quite suite your needs, you may want to consider reaching out to your hosting provider and see if they can copy your site onto a subdomain (i.e. dev.domain.com).

Some hosts may even have built in migration tools that can do it in a few clicks, and may be the easiest route.

If you do go this route, you may want to lock down the dev domain behind a password. Again, the host may be able to help with this. Otherwise, you can try this plugin: https://wordpress.org/plugins/password-protected/

Hope this helped,
– Casey