In Sprite Editor if I resize the image then the image loses quality in a very hard way. In any other external software I can resize an image and the quality much better. You must improve it. It's something simple and easy to do and improves game quality, performance, memory consumption and project size.
Of course it is possible to use external software but if there is a sprite with animations that contains dozens of images it will be much simpler to use the sprite editor just to resize the whole image together.