TikTok wants to further enhance features to remain competitive with YouTube
Full time horizontal screen mode could become the new feature the social media implements

A select set of users worldwide are testing TikTok’s new horizontal full screen option. Square or rectangular videos in their feed will now include a new ‘full screen’ button for viewers who have access to the test feature. The video will switch to a full-screen, horizontal mode when you push the button, making use of the entire screen of your phone.
The test feature is a way that TikTok is trying to be like Youtube. On TikTok, users can now upload up to 10 minute long videos. The company was hoping to attract the same category of long-form video makers that frequently post on YouTube. With less concern about the length of the video, creators now have greater leeway to film things like food, beauty, tutorials, instructional videos, comic sketches and more.
Given that the company has long-form material available, it makes sense for TikTok to improve both the viewing and creation experiences for users who watch these types of videos. If a video was originally shot horizontally, artists frequently add a ‘turn your phone’ remark at the beginning to urge viewers to fully enjoy the content that is going to play.
Some users may not appreciate the full screen mode, but TikTok is hoping to compete with other video platforms by implementing the new feature. TikTok may not make the feature available to all users until after it decides to formally release the final version. They may make changes prior to the formal debut. Currently, switching to full screen mode is by pressing a button, but possibly users will merely need to turn their phones sideways as they do with other apps.