Does resizing preserve the animation?
Yes. Every frame is individually resized while preserving the original timing. Your animation plays exactly as before, just at a different size.
Will the file size change?
Scaling down reduces file size, often dramatically. A 50% scale typically reduces size by 60-75%. Scaling up increases file size.
What's the maximum size I can resize to?
Up to 4000×4000 pixels. However, very large GIFs will be slow to encode and create big files. Keep it practical.