Yeah, it's long been known that good physicals are huge in the game.
Think people most commonly cotton on to it by noticing that they can go for advanced forwards with lots of pace and acceleration when they're on a bit of a budget relative to the league they're in. You also get these beastly target men knocking about. Not as commonly used by human managers but you sometimes notice them at AI clubs scoring loads, especially in weaker leagues.
Same thing for central defenders, where jumping reach is a big plus, pace and acceleration again if you can find them.
Don't think they're quite as important in some other positions but you still notice it. A common thing when you watch highlights is after clearance by a defender (kicked or headed) and when two players contest the ball. If you win it there by getting to it first because your player is quicker or stronger, and get away from your man then you can be running into space and you see a lot of attacks start that way when watching. Physicals must help.
I don't normally bother finding them specifically, but another one is that if you're lucky enough to have wide players with good jumping reach you can score lots of headers at the far post as full backs can often be small. The opposite is true, decent jumping reach full backs help prevent that.
Think another way to notice the importance of the physicals is just to look at how many players in each division have good attributes in those departments. In real football you might expect lower league players to be a bit better matched up in those terms, it's the one thing they might be relatively decent at if they were to play a higher team in the FA Cup etc. while not having anywhere near the skill. In FM they're always way behind on that too.
These from my current save:
PL players with 15+ pace 203 (20 clubs)
Championship 127 (24 clubs from now on)
League One 65
League Two 35
National League 13
PL players with 15+ strength 79
Championship 40
League One 23
League Two 13
National League 2
FM Arena did some similar testing on this - they too found pace and acceleration to be very important -
https://fm-arena.com/table/26-player-attributes-testing/
Edit: If you can't be arsed clicking, a team that would get around 60 points a season would get 81 if adding 5 pace to all their players, 80 if adding 5 acceleration, 72 if adding 5 jumping reach, 70 if adding 5 dribbling.
If you take off 5 points pace they only get 29 points.
Adding 4 points to all technical or mental attributes gets 75 or 72. It does make you better but not as much as a difference maker as honing in on the pace/acceleration attributes if you had choose and you can often pick up fast but relatively unskillful players fairly cheaply.