You might want to add text as a title to enhance your post. The way you do this differs depending on which layout you choose.
Discussion Layout
To add a title to your post in the Discussion layout, go to the plus icon on the top right of your post and select Title. You can then type the title to your post.

Video Layout
To add text to your post in the Video layout, go to the A icon on the left of your post and select Title. You can then type the title to your post.

You will see this title as an overlay of the card too. This can be removed in the Hub settings.

