There is several feature requests for this already, you may upvote: https://github.com/qbittorrent/qBittorrent/issues/9063

Here is an idea what one can do to reduce seeding of a high peer count torrents:

1. if you have some paused complete torrents, make sure to label these to reflect the reason for pausing
2. unpause all complete torrents
3. disable limit of number of actively seeding torrents (queuing) to make all torrents actively seeding (this will update seeder counts, longer to wait = possibly better?)
4. select to display only Seeding state torrents
5. sort all according to the Seeder count by clicking the column header
6. select all with high amount of seeders (lets say 10+) by clicking first one, holding Shift key, click last one), right click and set them label “High seeder count torrents tmp paused 2025-04” and then pause these torrents.

-> You end up seeding only low seeded torrents. After several months or a year, you can repeat the process.

I do not think that there is any option beside default automatic relocation upon torrent download completion. You can create symbolic link/shortcut manually.