Depends in exactly where you are searching on your Apple TV device and what you are searching for exactly.
The Apple TV device can hold many streaming apps and can search and find content from those streaming apps.
In many cases it can incorporate the apps' content into the search results if the apps allow it, so can show results for items not available directly from iTunes, but that may be available in installed apps such as Paramount+ or AMC+ or Amazon Prime, just to name a few.
Also, each individual app will also have its own search option showing its own content. If you look in the Netflix app for instance you will see content available only on Netflix. The general Apple TV search will not show results in the Netflix app because Netflix does not allow this.
The Apple TV app on your Samsung TV only has access to the Apple TV+ subscription content and the iTunes store movies and TV shows content, it has no access to other apps installed directly on your TV, so would be unable to search for and find content in other apps like Paramount+ or Amazon Prime for example. Only whatever is available directly from Apple TV+ and the iTunes Store for movies and TV shows.