I understand that with standard searching in SharePoint Online I need to add "keywords:" to my search query to search by keywords (ex. "keywords: Ford" when looking for all items tagged as "Ford" on a site about cars). However, I don't want the users to have to remember this syntax and I would prefer that they could type the keywords directly in the search (ex. "Ford") and have the keywords be included in the default properties that are searched. How can I do this with SharePoint Online? I'm unable to edit the "Searchable" checkbox of the "Keywords" property. I've tried using a RefinableString but that too does not let me change the "Searchable" checkbox.
Note - Using search refiners is not the solution though I've seen it mentioned in many articles. Search refiners only let you narrow down existing results by using keywords. They do not allow you to search by keyword.
I was able to implement Matthew McDermott's solution
Manage Query Rules
Search w/Result Block