Is it possible to improve reflexes for gaming?

It's hard to tease out what 'raw reaction time' even is, because reaction speed is so context-dependent. I'm going to crib from the wonderful book Bounce by Matt Syed (as far as I remember).

Set up is that Syed is a former Olympian ping pong (table tennis) player whose day job is as a journalist for the BBC. As part of a publicity stunt for Wimbledon or some other tennis tournament, they had a "journalists vs pro tennis players" series of matches. Syed was paired with Michael Stitch of Germany. He said going in that he didn't think he'd be able to return an pro serve (~135mph), but would at least make contact with the ball.

Yet when the time came:

I saw the ball go up, I saw his racket make contact, and I heard it hit the curtain behind me.

Oops.

Syed follows up with this:

My colleagues at the BBC may have just thought "oh well I just don't have the reflexes of a top athlete". But I do have those reflexes. The amount of time to you have to return a smash-kill in table tennis is 100ms, which is half the time it takes for a 135mph serve to reach you in tennis. I'm twice as fast as I should have needed to be.

He continues with the fact that a pro tennis player only "sees" the ball (and by extension an Olympic-level ping pong player) because of their expertise: they already have a pretty good idea of where it's going to be. But that expertise is domain-dependent (as Syed's anecdote demonstrates). I would imagine the same holds true for other amazing feats of perception, e.g. hitting a Major League fastball.

So your best bet, performance wise, is to become an expert at pinball. Play a lot. Get a machine with the glass removed, practice specific setups that you control by placing the ball. Get an intuitive feel for collision angles, etc. etc.

NOTE:

The quotes may be somewhat inexact, I don't have the book handy and am working from memory, but the gist should be correct.

While TheBird956's solution is helpful and will definitely help improve your reaction time, I am providing an alternative solution

While improving your reaction time is a part of improving your play in games like pinball, its not everything. You can also improve by getting more familiar with the game to predict when you would need to act and how (so its more preemptive rather than reactive) Once you start identifying the common patterns you know how your are going to need to act cutting down the dependence on being reactive

Yes it is possible.

In the past, I used this website to train my reflexes: https://aim400kg.com/ Of course training in the game in which you want to improve your performance is a lot better. The exercises in the website I linked are really generic and may not reflect perfectly in Pinball.

Like others said, you should train directly in your game and ideally play only that so you get used to predicting what to do.

With age it can take more time to practice, but I dont think you would have a major disadvantage at the age of 31.So take your time with it, you will get better at the game and with your own reflexes. Everything can be trained, but remember that you can also lose that training if you stop for too long.

Note: The website I linked is using flash which will be discontinued in a few years, so their minigames might stop working even before that. It is not known if they have plans to switch to HTML5 or something like that.

Also, I am not affiliated to that website, I just used it in the past when I wanted to get better at Overwatch.

Something I'm not seeing as much -

I have mediocre reflexes. I compensate by thinking ahead, planning out "If A then B", then when A occurs, I'm primed and ready to do action B.

It's a fairly useful skill, and one directly applicable to daily life as well. While it can look like reflexes, it's more pre-planning.

I think one should differenciate between "reaction time" and "quick reflexes".

In general, i'd say that your hand-eye coordination influences your reaction time more heavily than pure "reflexes". I've been playing video games for all my life, a lot of them requiring quick reaction, and (at least for me) there was a huge increase in reaction speed over the years. Of course, you're not gonna be a pro in e.g. Counter Strike just from playing pinball, but if you have played a lot of different genres your overall curve of reaction time in new games you start gets steeper and steeper. Thats because overall hand-eye coordination improves, so even if have no motor memory of the actions required by that game you'll become quicker at it faster.