I’m pretty sure that all of that are from extensions you would have installed for chrome?

No? Chrome isn't the only web browser in existence.

Whats [Spotlight-like global search] supposed to mean?

That I can bring up a search bar that'll search my history, closed tabs, bookmarks, open tabs, the web and more all at once.

Like pressing F12 for fullscreen?

Not only that, also selectively hiding the tab bar, address bar or specific sidebar panels.

Like themes?

No, like custom toolbar buttons that do custom things when clicked.