I created a character in illustrator that I plan to use in animations and on the web. When I shrink the vector to the size of, for example, a small avi picture for social media, I significantly lose line quality. How can I maintain the quality of detail? Is there a specific way that I should save or setup the document?
If you get distortions when scaling down, you may be facing the Align to Pixel Grid issue; you can turn that off in the Transform panel (two places).
If this is about a general degrading at small sizes, you may have to simplify the character so it is suitable for the size.
An image illustrating the issue might help helpers help you.
What file format, resolution and compression settings are you using? Sometimes depends on the image.
Most images you will save as ..jpg, and toggle art or type optimized (under imaeg size tab) hit preview to see result.
If you do not need many colors, you can use .gif to get sharper lines.