Possible to change the slug of default post type?

I have custom post types on my wordpress site and I’ve set the slugs to say “/blog/{post_type}/{post_title}”.

I’m using the default post type as a “notes” section, so I want that slug to be “/blog/notes/{post_title}”. Is this possible?

There are many »default post types« like post, page or even nav_menu_item. If you talking about post as the default just go to Settings → Permalinks admin page, chose »custom structure« and use /blog/notes/%postname%/ as your structure.