First of all, if you need a third row seat that can fit human beings comfortably and have some cargo space, go with a Suburban/Yukon XL. Secondly, I'd strongly recommend against a 2021 vehicle. Avoid first model years at all costs. With the previous (K2) generation, 2015s had pretty abysmal reliability.
As for the Sequoia, I looked at them extensively before going with a Suburban, the Land Cruiser as well. The 5.7L V8 is a beast of an engine, but the rest of the vehicle is extremely dated. I also don't like the way they package the options. If you want vented seats, you have to get the Platinum, which forces an air suspension on you (yuck). The interior is just lackluster though, especially for the price point. Yes, they're very reliable, but not worth that awful interior IMO.
I'd do a national search for a leftover 2020 Tahoe/Suburban/Yukon if I were you, otherwise check out an Expedition/Max.