'Tis the season
I coached high school-age basketball for the better part of 20 years - from high school varsity and JV down to church league - so I've known a LOT of kids who've gone off to college over the years, and I'd frequently see some of them when they'd come back home and stop by to say hello. These are kids who ended up everywhere from Harvard to military academies to small private schools to the Mega-U in a dozen different states. The thing that 95% of them had in common is that they loved wherever they ended up. That backstops your point that you can have an excellent college experience pretty much anywhere you go, it just depends on what you do when you get there. That's a bit of comfort as the parent of a current high school senior who ended up switching from a small, private women's college to Mega-U when she got her financial aid awards. As long as she stays driven and doesn't get distracted, she'll be fine either way.
Test-optional does seem to be the more common model, for the moment. But, for instance, the UC system is not just test-optional but "test blind" for 2022–2024. What happens after that, or on what basis they'll decide, I don't know.
I think you hint at this, but what effort a given student puts in depends a lot on what their peers are doing. This can cut two ways: the university I teach at has a very Greek/party culture and a very lightweight undergrad program in my field. I see a student or two per year who have at least as much aptitude as I had, who put in 20% more effort than their peers, but are still not working hard enough to be able to handle the transition to a top graduate program because their peers are really not doing anything.