I did a similar topic not long ago. I cut them back to about an inch below the top rim of the pot. The top of the plant got a small trim then I was able to fluff up the plant.

After they were pruned I lifted the sides of the plant and pulled out dead stems and pieces. I was surprised how much dead stuff was in there!

The constant high heat we've had since May 1st has done a number on them along with all of my flowers. They get more shade now.

This is what they looked like after the trim.

Saturn, Mine in a pot is just the same, nothing but greenery. I guess cutting it back can’t hurt. Maybe I will cut it back and feed it and get a second bloom. (Probably not but nothing ventured, nothing gained). It was spectacular for a while, but not now. I prefer annuals that bloom continuously throughout the summer.