You can make your block default to edit mode by adding this:
'mode' => 'edit'
I also widen the entire editor blocks by throwing this in my functions.php
//------------------------------------------------
// Admin CSS
//------------------------------------------------
add_action('admin_head', 'my_custom_fonts');
function my_custom_fonts() {
echo
'<style>
.wp-block {max-width: 1200px;}
</style>';
}