WordPress Installation Help

Hi,

I’m redesigning Welcome to Floating Doctors but the owners don’t want anything to be changed until the absolute last minute.
So I was wondering, is it possible to create their website on another website (such as a subdomian on my site I.E. https://www.test.trulyrandom.net) and then copy it over?

The only problem I can think about is that I’d have to manually change the links to every file. Is there a easier way I could go about doing that?

Thanks For Your Help,
Dan
TrulyRandom.net