As of January 2025, there is no official movie titled The Twilight Saga 6: Legacy. The Twilight Saga concluded with Breaking Dawn – Part 2 in 2012. However, fan-made trailers and concept videos have been created, such as the one you mentioned featuring Robert Pattinson and Mackenzie Foy. These fan creations are not official productions and do not represent any upcoming films in the Twilight franchise.

For a glimpse of the fan-made trailer you referenced, you can watch it below:

It appears that The Twilight Saga 6: Legacy does not exist as an official movie within the Twilight franchise, and any trailer you’ve seen is likely a fan creation or a concept video. As of now, there has been no confirmation of a Twilight Saga 6 in production, and no official trailer has been released for it.

If you’re referring to a fan-made trailer, these can be fun to watch, often showcasing the creativity of the fan community, but they are not official content and do not represent any future direction for the Twilight series.