There are many different ways to accomplish a staging site. One of the easiest ways is to set up your staging site on a subdomain. Then, migrate your WordPress site over to the staging domain. There are plugins that can assist in the migration process. Notably, UpdraftPlus has a special migration addon in their paid version that makes the process easier. Likewise, the ManageWP service lets you manage both staging and live sites from one interface.
There are many different ways to accomplish a staging site. One of the easiest ways is to set up your staging site on a subdomain. Then, migrate your WordPress site over to the staging domain. There are plugins that can assist in the migration process. Notably, UpdraftPlus has a special migration addon in their paid version that makes the process easier. Likewise, the ManageWP service lets you manage both staging and live sites from one interface.