Creating a "sandbox"

I’d like to redesign my site but not do it live. (https://www.sharinghousing.com) I’m wanting a new template and fearful about what might happen until I get it right.

I’ve searched on the Forum and all the answers to this are five years old.. so I’m wondering. I also found info on a development site in the Codex.
https://codex.www.ads-software.com/Running_a_Development_Copy_of_WordPress. Reading it stretched my understanding as I’m not a programmer. I assume it means that I would have to have wp resident on my computer – a MacBook. Is that possible?

I also found this: https://inspectelement.com/tutorials/create-a-wordpress-theme-development-environment/. That looks pretty good. And I can probably fumble my way through the directions. Thought I’d ask this community first if there is another way to go about having a development space that is simpler. Thanks for your help!