What does 'Spatial' mean in the iPhone 15 Pro Max camera?
What is the purpose of 'Spatial' in the iPhone? Why does it always ask to turn the camera to landscape mode to record video?
iPhone 15 Pro Max
It is a feature used to create videos for the Apple Vision Pro. See the information in Take spatial photos and record spatial videos for Apple Vision Pro with your iPhone camera - Apple Support including the following excerpt:
After you take a spatial photo or video, you can view it in three dimensions in the Photos app on your Apple Vision Pro. You can also view and share spatial photos and videos just like regular photos and videos on any of your other Apple devices. Spatial photos and videos sync to all your devices where you’re signed in to the same Apple Account and have iCloud Photos turned on.