Adding this because I didn’t see anyone else post it, but I found this guide really useful for setting them up: https://trash-guides.info/Hardlinks/Hardlinks-and-Instant-Moves/

It’s linked to on the official wiki, and walks through the process of Hardlinks and Atomic Moves. They’re basically shortcuts, they allow the file to exist in two places at once. This means you can still have a torrent seeding, while the media also exists in your plex collection. It also “moves” the file instantly once it’s finished downloading, without having to wait for it to copy anywhere.