Testing new theme while still hosting existing/old one

We’ve use an old version of Avada theme and want to change to the latest Avada. (I am a novice.)

I want to build our website using the latest Avada and once completed have it replace the current website. (My host will swap over for us)

Is there an easy way to do this or do I need a new access for WP? Can this be done using the same access we have for WP?

I have see some references about a plugin called Theme Test Drive, is this the best way to achieve what we need to do? Or is there another better option?

We have the new Avada theme files on our laptop and not sure what to do as we don’t want to risk stuffing up our current site.

Thanks, Alan.