OnionShare lets you securely and anonymously share files of any size. It works by starting a web server, making it accessible as a Tor Onion Service, and generating an unguessable URL to access and download the files.
It does not require setting up a separate server or using a third party file-sharing service. You host the files on your own computer and use a Tor Onion Service to make it temporarily accessible over the internet. The receiving user just needs to open the URL in Tor Browser to download the file.