I recently bought a Certified 2018 XF S from the nearby Jag dealer.
It had the same full-size headrests on the two outboard rear seats as it had on the front seats.
They blocked the view out the rear so badly that I decided I had to remove them.
They were so tall I almost couldn't get them out for lack of clearance.

The middle seating position has a nice short headrest - and I thought "get two more of those".

Then I saw other XFs where all three rear seats have the short headrests, like these...

Low profile rear headrests

I had the tall ones from the front in the two rear outboard seats as well.

Was this an option of some sort? Or maybe someone swapped them for some reason?

Tx

 

There's a button on the side of them you push and they flop down...............

 

On my XF Sportbrake it's the same thing-- the center rear headrest is entirely different from the other four, and is similar to the three rear headrests pictured. And the two larger headrests absolutely block visibility. And while yes, there's an obvious button to fold the larger ones forward, they are far more obtrusive than the center headrest even when folded forward, which I believe is the OP's issue, and I agree.
I've never seen the three small headrests.
FYI, here's a single one (in "Oyster") on Ebay to give you an idea of price.
(Other option, which I'm going to do, is simply keep the larger ones in the back and put them back in if you have need of them.)
https://www.ebay.com/itm/143894696311

 

North American spec cars have the big headrests, EU spec cars have the smaller ones as pictured. Not sure why.

 

Maybe its because North Americans have big heads...