Hi!
You can change the width of the results box here: https://i.imgur.com/XPBYvCv.png
That’s what you are looking for 🙂
The gap between the search and the results container is set here: https://i.imgur.com/QVk0CVy.png
You can set even negative values (like -10px) if 0 still gives you a big gap.
This documentation will help with enabling search in the product attributes.