All networks are different and follow different rules when it comes to images sizes.
To prevent your images from appearing pixelated or not at all you should make sure to consider each network's individual requirements for image sizes. Images that are too large or too small might appear blurry or will not be posted at all.
Twitter supports images with
- a minimum dimension of 144x144 pixels
- a maximum dimension of 4096x4096 pixels and less than 5 MB.
Twitter supports JPG, PNG, WEBP and GIF formats.