Show author headline under title

Got it now. Now it doesn't need to go to edit post, it has display rules on the element.

Well, it's not looking nice. Can I make it look like a box?

The author name and description should appear in box.

And can I move those details like

Publish date,
Author name,
description

in the sidebar?

At least, I want to make them look like a natural author box.

How can I design?

Let's keep one question at a time.

It's tough for us to tell what looks nice or not - can you provide an example of what you are trying to achieve?

Have you considered using a block element post meta template?
https://docs.generatepress.com/article/block-element-post-meta-template/

As you can see the author here on this page (link added privately) the author bio is completely a seperate entity.

If I added the text through block and add it. It sounds like a it's a part of content.

Can I design my block to make it different from the content?

Like a seperate box?

Hope that it's simple and clear.

Are you referring to this section?
https://www.screencast.com/t/5tfZNbVxofwW

If so the Block Element Post Meta Template (mentioned above) with dynamic data would be what you are looking for:
https://docs.generatepress.com/article/dynamic-data/

Yeah, thanks. I shall give it a try if I could.

Sounds good :)