How Can I Get Splash Page and WP CMS in root Directory?

I am working on a project for an artist and she referenced this site: https://www.kinagrannis.com/

I notice that this WordPress Installation has a ‘splash’ page with the really important stuff for this artist on it and then a “Continue to KinaGrannis.com link that goes to https://www.kinagrannis.com/home/

It does not look like WordPress was installed in a sub folder or subdomain. So how was this achieved so that she has everything installed in root but has a splash intro page and a home page all at the same level?

Thanks for any answers you can give!