In Exchange, whether it is 2013,2016 or 2019, you have a list of Transport Agents. To view them you can run the following command:
In the scripts folder with the Exchange installation directory you can install the Anti-Spam Agents Transport Agent using the PS1 script, to do so you need to navigate the scripts folder and run it, this is what the output will look like or similar:
You need to restart the Transport Agent for it to take effect. Once installed, you will notice you have them listed now, the count went from 9 to 14.
Hope it helps.