By default, the Agent doesn't come with a lot of plugins, you can list all the plugins with the following command:

PS C:\App\Agent\agent_13.3.0.0.0\bin> .\emctl.bat listplugins agent -type all
Oracle Enterprise Manager Cloud Control 13c Release 3
Copyright (c) 1996, 2018 Oracle Corporation.  All rights reserved.
---------------------------------------------------------------
oracle.sysman.oh    13.3.0.0.0           C:\App\Agent\agent_13.3.0.0.0\plugins\oracle.sysman.oh.agent.plugin_13.3.0.0.0
oracle.sysman.oh    13.3.0.0.0           C:\App\Agent\agent_13.3.0.0.0\plugins\oracle.sysman.oh.discovery.plugin_13.3.0.0.0

PS C:\App\Agent\agent_13.3.0.0.0\bin>

To deploy the plugin, we have to download it with the link from the OMS (Please check the OMS section).