Yeah, the OP can literally just be whatever you would have posted if it was a standard reply in the original thread. The only thing “extra” is just picking a name for the thread. And since it links back to the original thread, and it can even link back to a specific post in the thread, all of the connection is done for you. And that link goes both ways; the post you started the new thread from, as a reply, has a link to the new thread. And the new thread OP has a link back to the original.
Here is a real example of one I did just a couple of weeks ago:
That whole OP was originally going to be a reply in a P&E thread, but I was worried that going into what kind of drones were needed to drop bombs would be too much of a tangent. And since it was no longer about anything political, but was just about technology, I decided to put it in a different category other than P&E. But really, all I did was choose to “Reply as linked topic” to a post rather than a normal reply, changed the category, gave it a thread title, and posted the same thing I was going to post as a reply in the original thread. It wasn’t much more of a hassle than a normal reply. And there was no technical reason for changing the category; it will default to the category you are already in, that was just a choice I made.