By default, the Snapchat app records videos in portrait mode. However, if you would prefer to record your snaps in landscape mode, the application offers a quick solution to change your default video format.
Change Default Camera Orientation on Snapchat
Open Snapchat and tap on the Settings menu in the top-right corner (represented by a gear icon):
Next, scroll to the Advanced section and tap on Video Settings:
Tap on Camera Orientation and select your preferred default camera option. The Standard option will keep your videos in portrait format, while the Rotate 180° option will record videos in landscape format: