Apple TV+ Box

No. Depending on what you want to do exactly.

If your Smart TV supports the Apple TV App, you do not need an actual Apple TV Box. If all you want to watch is movies and TV shows from the iTunes store as well as content from the Apple TV+ subscription service.

You cannot however, use the Apple TV App on your TV to watch content from your computer that was not purchased in iTunes. If your TV Supports it you can AirPlay content that was not purchased in iTunes from your computer.

The Apple TV app on smart TVs is not a full replacement of the Apple TV set-top box. The Apple TV box offers many more features.

The Apple TV app on third party streaming devices offers access to:

• the catalog of iTunes Store movies and TV shows (buy and rent);
• the Apple TV+ channel featuring Apple Originals (subscription);
• other premium subscription channels.

The Apple TV box offers additionally:

• thousands of third party apps;
• integration of some of these apps in the Apple TV app (Watch Now and Up Next);
• Home Sharing;
• AirPlay;
• iCloud services, including optional Apple Music subscription access natively;
• HomeKit home hub functionality
• etc.

No, if your Smart TV supports the Apple TV app you will find Apple TV + within the Apple TV app. However, IMHO I like the experience of using an Apple TV much better than using Smart TV's interface. If you want, you can order an Apple TV 4K or HD from Apple, they have a 14 day no questions asked return policy to try it. Another huge advantage of doing so is it will entitle you to 1 year of Apple TV + when you buy an Apple TV and other qualifying Apple products such as a new Mac, new iPhone etc...