Sonarr and radarr can download files, but you cant set it to not download more than 5 episodes unless you do it manually. There is an arr app that auto deletes files older than X days (I forgot the name), but you also have to delete torrent files to get more space (this part can be done by setting up qbittorrent to auto delete after some time, but then you might have issues with your trackers unless you are using public or usenet).
Jellyseer is just amazing GUI that can be used instead of loging in to radarr and sonarr, allowing you to press just one button to request media.
I think arr stack is amazing for downloading (automated or manual), but you might need extra thinkering to not fill up your storage. 12 TB is more than enough for me, but I only use 1080p.
My 12 TB is filling up around 1TB a month, so I will just free up 5-6 TB manually every 6 months. Well, thats the plan at least, time will tell