A wide 1280×720 frame
The X recipe writes a 1280×720 (16:9) MP4 with H.264 video and AAC audio, at your video's frame rate up to 60 fps. A 1080p or 4K landscape video is scaled down to 1280×720, and one that is already 720p keeps its size.
If you would rather keep full resolution, ask ToolGPT for a plain MP4 conversion instead. The recipe always produces 1280×720.