Hey there! I also got tripped up by this when I was testing things out. "Styles" are specifically something that can be applied to a "Theme" so it's best to think of the theme as the parent. Right now, we have Paper Lantern and Jupiter as the theme, but there are currently no styles available for Jupiter.
You can still switch the theme in WHM through Modify an Account or by editing a package. You can also switch directly inside cPanel in the right-hand menu "Theme" section drop-down. Note, there is an issue trying this from the cPanel drop-down in Firefox, which we are addressing in case CPANEL-37391.
Let me know if that helps clear things up!