How to test a new wordpress template without touching the main site?

Question

Design

There is a working site on wordpress with a certain attendance. I want to put a new template and test it with the data that is on the site. How can I make this so that while I'm testing the template, the site remains unchanged and working? And so that I can easily upload new changes to it later?

Answer 1

1. Copy the content and base. Expand locally.
2. Upload to the server. Customize and preview without activating