Yes there are several options, developing a new theme using a local WP site for testing. I assume you already know how to create a WP theme.
The local site could be a copy of the live site to make sure it works as intended. Then import the new theme to the live site and use it, the switch can be reversed if there is any problem.
Please read this post too: https://www.sitepoint.com/community/t/using-localhost-to-develop-clients-website/245236/5?u=erik_j