Anna's Archive has a tool that let's you enter a max file size and generate a magnet link with files that need the most seeds: https://annas-archive.org/torrents#generate_torrent_list
If you want a .torrent file instead of a magnet link, you can use this tool: https://github.com/cparthiv/annas-torrents
Not piracy related, but Distributed Denial of Secrets has a bunch of leaked data, it's basically like WikiLeaks. They have a guide for seeding on GitHub: https://github.com/ddosecrets/torrent-mirroring, I mirrored it on Codeberg in case it gets taken down: https://codeberg.org/andromxda/ddosecrets-torrent-mirroring/