Your Apple TV box (3rd generation) [A1427] should be able to play Apple TV+ movies without needing AirPlay. Apple TV Software 7.3 or later (v7.9 recommended) brings the modern Apple TV app. Update your Apple TV - Apple Support
Your Apple TV box (3rd generation) [A1427] should be able to receive Apple TV+ content from Mac and iPad. Especially on Mac, note to use the in-app AirPlay function, instead of screen mirroring, as this content is protected to not be screen captured.
Select newer Samsung smart TVs (2018+) can receive AirPlay streams without needing an Apple TV box. Then you could receive up to 4K resolution streams, if your TV is capable of that — while Apple TV box (3rd generation) is maxed out at HD resolution.
Select newer Samsung smart TVs (2017+) can have the Apple TV app or Apple TV+ app. Then you can stream without AirPlay and without Apple TV box, for Apple TV+ content.