How to get Block Plugin Id? when block created using block type entity? I have created the Block type entity using Drupal 8 UI. Now I have to Place that block entity programatically in theme region. The related question discussed. 
Here

As solution given by @Shawn Conn is fine when we define our own block plugin class. As in my case I don't. I created Block type using UI
You use the custom block uuid:

'plugin' =&gt; 'block_content:' . $custom_block-&gt;uuid(),