Do you also not adjust monster’s DCs, or their saves, or damage, or hit rates as the system assumed CR increases?
Yes/no, depending on how you look at it. To me, it's more about "what threats would the party be nudged towards" rather than "adjust the threats to scale with the party".
For something like D&D 5E / PF2e creature rank, I generally wouldn't adjust an enemy's CR to match the party. What I
would do is nudge the party in the direction of appropriately severe threats worthy of their time, and hand-wave away pointless encounters (especially so in PF2e, where leveling factoring into combat proficiency and how the critical hit/miss rules means that a significant level difference has massive mechanical differences).
To make that more concrete, for a higher-level D&D 5E / PF2e party that might once upon a time have had to deal with the odd low-level bandits when traveling a major road between towns, they aren't automatically going to run into ambushes of wildly powerful bandits waylaying travelers on the very same roads. I view that sort of thing (
Elder Scrolls-style "world levels with you" concept) as anathema to having the world make any sense at all. However, I wouldn't bother wasting the players' time with the same low-level bandit encounters, either -- we can hand-wave this vaguely as the party perhaps having established some reputation, or somehow
looking like the powerful adventurers that they've become; and your average highwayman wouldn't suddenly commit suicide by attacking them when so severely outmatched.
On the other hand, that group is rather more likely to find leads, employment offers, etc. that would point them to higher-level threats that
always existed in the world, but weren't necessarily plausibly in reach. Maybe they needed to clear some site in order to be able to find evidence that would point them to elsewhere, maybe it's literally a matter of reaching a deeper and more heavily secured floor in some underground complex, maybe the party didn't have the reputation beforehand for the patron to even consider reaching out to them, and so forth. NPCs wouldn't have a concept of character sheets, but they can assess things based on what they've heard about a party's accomplishments and apparent capabilities versus what they've heard or inferred about problems and threats.
But, generally, those higher-tier threats were
always there, and at a power level appropriate for their own nature. If, say, I were running a low-level PF2e campaign in the Gravelands region of Golarion and for some reason the party absolutely insisted on trying to storm the infamous many-millennia-old lich Tar-Baphon's stronghold on the Isle of Terror -- well, I'm not going to pull any punches and they're going to face (very briefly!) the
extremely lethal threats that would logically be there, not that Tar-Baphon himself even has an official statblock in PF2e.