I have an ‘18 SR5 with 3 row. 2nd row seats slide and recline. The seat bottoms do not flip forward when folding as they do with 2-row models. There is some space, maybe a couple inches to the back with the raise in the floor, behind the 2nd row seats when pushed back to their maximum.
I’ve used the 3rd row only once, that for a small adult man and a child. I personally cannot access the rear seats; too old, not too limber. There are two individual seats, one can still be folded while the other is in use. When the 3rd row is in use, there is virtually no room between the seat back and the rear hatch. I had to empty the cargo area and leave behind all my usual carry ons (extra water, a jump start pack, a small to-go bag) as well as my cargo mat and privacy cover.
To see how much space in the cargo area that you loose, check out one of the 3rd row delete threads. With third row, the cargo floor is several inches higher and even with the lip at the rear. That allows things to roll out and fall to the ground if you are parked on an incline. I found that out the hard way when I first bought the rig and lost a 1.5L bottle of Jim Beam … :crybaby: I solved that, somewhat, by purchasing the Toyota cargo net that runs across the hatch opening. It doesn’t stop things from rolling out, but since it mounts folded in two, it creates a full length pocket to hold things.
Note that if you purchase privacy covers and cargo nets that designs and part numbers are different for 3 row and 2 row models.