All Volvo wagons (V40-70) have built in boosters, have done for yonks.
Older V70s also have factory built in ****ie seats.
Check each one out, some have centre booster only, some have one on both sides.

I have a 97 V70, with a centre booster. With it up, I would easily get two rear facing capsules in the car as well. With it down, using proper car seats, I could get 3 across the back, depending on the seat.