The preferred way to use Tdarr. Specify one or more plugins.
Plugins can be found on the 'Plugins' tab. Use Community plugins or make your own and add them to the 'Local' folder within the Tdarr Plugins folder.
Copy a plugin ID from the 'Plugins' tab, paste it in the Plugin ID input box in the transcode options, select the type of Plugin (Community or Local), and hit Enter to add the plugin to the stack.
More info can be found in the Plugins section here