You can set up quality profiles in Radarr/Sonarr and they can get very specific through Regex. You can also set up the root folder to your Plex folder for them to get downloaded there automatically.

Yesterday I finished automating my seedbox and oh my, it's so so good. I gave my family their Plex accounts and they're so happy getting any movie or tv show they want in two clicks in any device they have. Plex->Overseerr->Radarr/Sonarr->Download, it was so satisfying to set up, a lot of fun too haha. I even set up a Telegram bot so they know when their requests are available.