WordPress offers the ability to register block templates for the block editor programmatically. This plugin adds a UI to the WP Admin to add block templates without having to be able to program. So if you want every new item of a specific post type to start with a default set of blocks, you can make it happen with this plugin. No programming skills required!

Furthermore, for classic themes (unfortunately not for block themes), it adds the option to edit the content of post type archives and taxonomy archives.

Block Editor Templates