In order to use the Page Builder in Blog Posts, you need to enable it by going to WP Bakery Page Builder > Role Manager > Post Type > Custom > and selecting Post
When you have the WPBakery Page Builder enabled for Posts, the excerpts aren’t generated automatically. You need to insert the excerpt manually for these posts.
To do this you need to enable “Excerpt” option in the Screen Options menu in the post editor then add an excerpt for your post as much content as you need.