How do I change a video from vertical to horizontal. I have iPhone 11. Thank you.

To view just tilt the iPhone.

Make sure orientation lock is not ON.

Swipe down from top right to view Control Centre, tap the icon with a lock and a circle arrow around it to lock/unlock screen orientation.

If you have already taken it you can't.

This won't work after they have already shot it in portrait mode. It will just give you a smaller version with large black bars on the side.

Yes, it won't convert, but it can be viewed in landscape though.

It isn't really in landscape with the wide black bars. I believe the OP, considering the link they came here from, wants to know if they can edit it to make it a landscape video.

You're right.

I meant landscape for viewing, not meaning that it will take up the whole screen or do conversion.

I missed the link at the top though.

I guess OP wanting some magic.