It does apply to anyone, but it is more or less meaningful depending on where you start, so the meaningfulness isn't equivalent.
It's as if you say you can double your money, but it only works once and with a value < $1.
The idea that, say, Magnus could increase his chess playing abilities in 6 months (or even 6 years) to be able to beat the current version of himself 99% of the time would be insane.
Trade offs may be something like in yours teens and early 20's your brain may have the most plasticity and ability to visualize (plan 10+ moves ahead) but you might not have accumulated enough experience.
I'm purely speculating here and just wondering aloud. (I bring it up in response to this comment because Magnus' prodigious talent is so noteworthy I wonder when Magnus will stop being able to "beat" Magnus of 1 year ago.
I think there are a lot of confounders to consider. Though GMs like Anand show a drop in standard rating (https://ratings.fide.com/profile/5000017/chart), his blitz rating is near his all-time-high (ie. is his standard rating drop due to decreased mental performance or a shift in interest/focus to blitz?). Similarly, I suspect a lot of strong players who fall in the `2000<FIDE rating<2300` realize they may not be the next magnus and shift focus when/if they make the decision to pursue a career outside of professional chess.
While this doesn't answer your question, it's interesting to note Magnus's peak rating was actually 7 and a half years ago, when he was only 23.
With the exception of Anand at 51, they're all quite young.
So yes, performance does fall off with age, though not as intensely as something like hockey.