well i have tried to be more careful with these phones since I know there is glass on the back etc. unlike the V20's we used to run. Those were pretty freakin rock solid with UAG cases on them and I've been a UAG bigot for years. But a review I saw on flimflamazon of a UAG case for the Oneplus 9 Pro showed the phone it was in cracked all to shizz from dropping it and a horror story to go along with, so I didn't bother with a UAG. Tried one other that looked heavy duty, a 2-piece snap together puzzle piece thing but it was a joke.
Ultimately settled on a Spigen Tough Armor. It is not a heavy as the UAG's I used to use but it works well and thus far, about 8 months into these phones, it has protected my phone well. Including a couple of drops. It also works with the OnePlus 50W Warp wireless charger, although I do sometimes "lose connection" (blinks red til you remove and replace) on mine. My wife's with same case doesn't ever do that on her Warp charger. *shrug*
EDIT PS: This case also works very well with the Whitestone tempered glass screen protector kit