No plugin is necessary. On the source site:
1. Disable any caching plugins.
2. Export the database to your local computer.
3. Via FTP, download all files.
On the target site:
1. Create a new database. Write down the user and password you create for it.
2. Edit wp-config.php (which you downloaded above) and put in the new user and password (and the db name, if you had to change that, as well as the db host, if that changed).
3. Import the DB onto your new site.
4. Upload your files via FTP.
If you changed the domain, use the following script to search for https://youroldsite and replace with https://yournewsite. https://interconnectit.com/products/search-and-replace-for-wordpress-databases/
That’s it. Aside from the time to download and upload, it’s a very quick process.
