my guess is very few people, no matter how many times it's suggested, will get a bike fit. folks are spending $700 on a frame, so $200-300 for a bike fit may be difficult. i'm all for bike fits (used to do them) but i understand the friction.
truth is most people are still think of choosing a bike like buying a T-shirt (small/medium/large/etc). in the simplistic terms that's technically true, but yes, it can be super complicated too. but i also think the newer you are, the less the subtleties will be noticed. i remember adjusting the saddle a few mm up/down/forward/rearward for my wife and kids' bikes. no one ever noticed! :-). ok, maybe my son appreciated me raising and moving the seat a bit when he was growing like a weed :-)
as for dropping the saddle, i went through something similar when i got my gravel bike 2 years ago.
i thought i knew my measurements after years of road riding and transferred them fairly closely to the gravel bike. but i felt just a bit sketchy on descents still, kind of top heavy despite the bike having a greater bb drop and slacker head tube angle, etc. so i dropped the saddle 5mm. the lowering of center of gravity, really being able to weight the outside pedal, a little more flex in the knees to absorb bumps, all made for a huge difference. also felt more power at the bottom of the pedal stroke.
i decided to drop my road saddle 5mm (and back a little to compensate) and same benefits! felt a little too low at first, but within a few rides, i was setting descending PRs and even some climbing ones with the added power. a few weeks after that, swapped to shorter stem on the road bike too and could more easily get in "puppy paws" and stay in the drops, etc. just shows age, loss of flexibility, etc. sneaks up on us.
maybe that'll take some pressure on some of the newbie folks getting their fit absolutely right. '
a new bike will always take some getting used to. and if you're newish, you may not be all that set on your old fit. give it a few rides. if it feels off, make some minor adjustments (seat back/forward, up/down, etc) and ride a few more times and see if it feels better. bummer is with the new integrated cockpits you lose the ability to easily and relatively inexpensively swap to a different stem. i have a couple shoe boxes of old 26 and 31.6 stems from 80-140mm from the various mountain, road, tri, tandem bikes we've had!