Evernote will do this, you can feed it a bunch of PDFs and other documents, it will OCR them and make them all searchable. it's not perfect, but you can also add manual tags for things you know are important.
I wrote a scraper to download all of the California EdCode from the governments site, convert them all to txt docs and I can ask questions about California EdCode in plain English.
I work in a shared governance capacity that requires us to refer to the Ed code for contractual negotiations and it’s been extremely helpful.