Hello
Yes, I think I might replied to you in a YouTube comment already, but if it wasn't your question, here is the answer.
It's just one checkbox, but it also depends on what you want to achieve. Some games show hands, and some show only a crosshair, these elements would have to be adjusted by you. By default Atavism is just moving the camera into your player position, your job would be to hide it, make it transparent, show hands, or whatever you would want.
Yes, the mentioned checkbox is turning on your first-person view, but there are also more options, like rotating your character towards your camera view, Camera Follow Mouse, and more.
A top-down view is also supported out of the box, so it's as simple as adding one component to the camera and setting it to your needs. it's related to the click-to-move controller and more information about it you can find here https://unity.wiki.atavismonline.com/project/how-to-set-click-to-move-controller/
I would recommend you try to install the 14-day trial version and see if this is what you are looking for https://atavismonline.com/home/atavism/atavism-on-premises/atavism-2018-op-standard-subscription