Frontmatter on Add New Page

I'm new to GRAV and it suits my usage, so all is good.

I am trying to make it simpler for my case and have managed to add a Plugin that creates a 'new' post/page under my Blog section. When I do this it has what I think is default Frontmatter

Title:
Date:

I'd like to include other Frontmatter automatically. There must be a file somewhere that is writing the default matter, I can't find it..!

Any pointers or help appreciated.

I don't understand what precisely the problem is. Your plugin can add whatever you want it to.

Here's the doc page that talks about frontmatter, including their default settings and how to use frontmatter.yaml.

There's no one place in the source code where the defaults live. Here's the code that processes frontmatter. Some defaults are set in the init function.