Does not appear to be. It seems that you need to create your event calendar using code like this in a note:
```joplin-plugin-event-calendar
group: day
events:
- date: 2012-11-05
icon: 🔥
title: Bonfire night
text: We have been collecting wood for a week now...
bgColor: orange
```
The plugin site you linked to above also contains the instructions on how to use the plugin.