First off congratulations!
I have a 2020 CX-9 Signature with the Captains chairs. We started with Graco setups since we like to click in and out of the strollers. Nothing wrong with any of the other name brand setups like Britax we've just had nothing but good things to say about Graco's stuff. Their customer support is also top notch.
Once you've committed to a quality brand (again, don't go cheap!), its fair to acknowledge there are a multitude of models. Its worth comparing them side by side to sort out if you're actually paying for features or just marketing at that point.
I also 100% second the advice to stop by your nearest fire station to have them check out you've installed it correctly. Even better, many places have scheduled car seat clinic days where they clear out the fire station bays and you can actually drive inside to get it checked out. Calling your local hospital's maternity department is a good place to start if you don't find the dates just searching their website. Here in Minnesota, our hospital sent us home with dates and contact info after my son was born. The car seat clinic people are genuinely glad to help out, just remember the manuals for your car seat and your car.
While I can now install these seats in my sleep, when we first bought them it was not nearly so obvious how to do it right.
My my younger infant son we have the Graco "Graco SnugRide SnugFit 35 DLX"
Read reviews and buy Graco SnugRide SnugFit 35 DLX Infant Car Seat Featuring Safety Surround - Jacks at Target. Choose from contactless Same Day Delivery, Drive Up and more.
www.target.com
For my older son, we bought the Graco 4Ever 4 in 1 seat since we could pick it up at Costco when he was too big for the infant seat. We still have it facing rearward and it fits great. It looks like the "base" 4Ever model we bought is discontinued but I'd have to imagine the newer DLX model, etc fit just as well.
Read reviews and buy Graco 4Ever DLX 4-in-1 Convertible Car Seat at Target. Choose from contactless Same Day Delivery, Drive Up and more.
www.target.com
Finally, these were recommended to me by another guy on this forum and they are worth every penny (they are not expensive to start with). They also install in roughly 15 seconds.
Read reviews and buy Munchkin Brica Deluxe Kick Mats - Black 2pk at Target. Choose from contactless Same Day Delivery, Drive Up and more.
www.target.com