Improve Ride on 2013 BRZ
 

I know there are many threads about this, but they are a little bit older and I just wanted to get some opinions on what I could do to get a smoother ride out of my 2013 BRZ. Some suggestions are to get shocks and springs from newer models, but up to what year will fit in the 2013 model? What would be a good aftermarket option? Is there anything else I can change to get a smoother ride?

buy another car.

stock shocks/springs from a 2017-2020 would be great, just make sure it's not from a PP car.

Anything you do will provide minimal gains IMO. Not worth the effort. It’s a sports car designed for corners. Just enjoy it.

Improve Ride on 2013 BRZ
 

I disagree. I did this exact swap, almost new 2017 86 shocks and springs on my 2013 BRZ. There was a significant difference in ride comfort and it was totally worth the $250 I paid for the set and the few hours putting them in.

I have a 2017 and don’t think it is noticeably different to all the earlier ones I have driven. Each to their own.

+1 to the 2017-2020 OEM suspension from a non-Peformance Pack model.

You can also consider downsizing to a 16" wheel so that there's more sidewall to cushion the ride. Depending on the wheel width, use either 205/55/16 or 225/50/16 tire to get close to the stock overall diameter.

This. Adding as much sidewall as you can, and driving on a non-performance, non-runflat tire is going to make a massive difference over smaller bumps and gaps.

I am with you. I went from the 14 with lowering springs to the 20 and other than not hitting the bump stops with things like RR tracks or driveway transitions I don't feel that great a difference. I REALLY hate the feel when I go to my 16" snow tires even when they are colder. There is nothing quite like having sidewalls start to roll under in a turn.
Strangely enough I would want the opposite of the OP anyway. If it was all soft and floaty I would not like it at all. Any suspension that isolates your from the bumps to any degree also numbs the whole feel of the car. May as well have a BMW or Mustang at that point.

I don't think any year BRZ has a smooth ride

A '75 Cordoba with rich Corinthian leather has a nice smooth ride....

I have a 2015 Fr-s first with Eichbach prokit springs on oem strut and now with ST Suspension XTA. The suspension is set at soft and the ride is way better than before. Bumps are less harsh but the felling and control are way better. I bought it slightly used and waited before installing it not sure it was necessary for me. Really happy with the result, and the car is lowered just like with the Eibach springs.

Be handy if you knew someone with a 2017+ so you could go for a ride and see if the difference is worth the effort to swap suspension components.

This is the best recommendation.
Pretty sure that confirmation bias plays a part in the conflicting reports of how much difference there is between the two. I went into it not expecting much difference so that is what I feel. Somebody swapping over and anticipating a huge change will feel a huge change. It is just how our brains work.

It wasn’t a huge difference IMO, but significant.