Swapping URL of Custom Domain


When my app is undergoing changes, I will test them out on a copy of my app first then apply them to the live app.

As not to disturb my users, I created another maintenance app that is linked to a single sheet, where I will swap links with the live app when applying the changes. When doing this, will it also be the same when doing so with the free app? With DNS settings involved, I’m not sure this will be possible.