Natively you can't use a formula to convert the file on demand/within QB itself. Depending on how large your files are though - you can use the downloadFile API call per your comment and log/write the api response into a Text field in QB. Basically when the file is uploaded/when your pipelilne runs, use the Quickbase Request channel to make the downloadFile request, and write the response value back to a text field dedicated to this.
If you're using the Pipeline to make the API call to another system though - you can just perform the downloadFile call during that process and do the same. No actual need to write back to QB.
