This repo will help you do daily update blocklists, you can check https://gist.github.com/shmup/29566c5268569069c256 for detail and use https://github.com/magicshield/transmission-blocklist/releases/latest/download/blocklist.gz in your setting.

here's how to do settings.json:

add to you settings.json

"blocklist-enabled": true,
"blocklist-url": "https://github.com/magicshield/transmission-blocklist/releases/latest/download/blocklist.gz",

verify by command:

$ transmission-remote -n admin:password --blocklist-update
localhost:9091/transmission/rpc/ responded: "success"