Hello 360vids,
Welcome to the
PhotoDirector forum if you've not been welcomed before. Welcome in any case.
The purpose of a cinemagraph, or Motion Still in PhD terms, is to create a looping animation. PhD exports these in GIF format only, because that's the most appropriate format.
As far as resolution is concerned, you can export the GIF in
high resolution (i.e. the resolution of the original video), but that takes more processing time & results in higher file size. These may not be significant considerations for you.
e.g.
Original video: 1920x1080 - 11 sec - 17.5MB
Exported GIF: 1920x1080 - 25.5MB, 1200x675 - 10.8MB, 960x540 - 7.25MB
PIX
PIX YouTube channel