Strategies for keeping library size in check

[zapp7]

I'm looking for a way to automate deletion of media to help keep the library size in check. I'm running jellyfin in docker on ubuntu and have multiple users requesting stuff with jellyseerr.

I have tried to create a bash script that deletes files older than 6 months, but that has proven complicated because my download client preserves the original modification time stamps (I.e. the modification time often predates the download date).

Any other strategies to achieve something like this?