I've done searching and come across a few threads but so far I have not been able to search by model from the top search bar. You have to go into the search and check the box. All of the suggestions don't affect the search functionality. If it matters, I'm using the Novator template. Any other suggestions?
open file public_html/extensions/novator/storefront/view/novator/template/blocks/search_top.tpl
and add <input type="hidden" name="model" value="1"/>
inside <form> tag.
Note: if you plan to upgrade cart in the future this modification will be overwritten
Thank you for the excellent answer, this worked perfectly.