I can’t recommend Paperless enough. I set up email forwarding to the Paperless ___domain and it automatically downloads the attached documents. The only problem I have now - I am using a somewhat older version and there’s no direct migration path to the recent one.
https://docs.paperless-ngx.com/
Think: replacing paper file folders with a digital system. Supports OCR, a variety of metadata, tagging and categories, etc.
My primary use case is taxes, but for any important legal or financial documents, I throw 'em in Paperless.