Been there! Just search: "rent car near me" online and youll find tons of instant booking services. Heres one that usually has same day availability https://getrentacar.com/en-US/car-rental . Their prices are normal, in my opinion. Although, of course, it is much better to book a car in advance, this is not always possible.
These tools are great for spotting technical issues though they might miss some nuance. I usually cross-reference data with Google Search Console for better accuracy.