@The D of W
Not sure what is meant here by a "pressure change".
The alternative to the drain/fill/wrinse/repeat is a device that allows the transmission's
own pump to push out the old fluid into the device's waste reservoir while drawing in new fluid from the device's supply side. Since it's own pump does the work, there is no unusual pressure involved. The device is installed inline between the transmission cooling line and the coolor inlet on the radiator or wherever else a given vehicle manages the cooling of the ATF. These aren't always easy to access, so it takes a shop with some knowhow to do it properly.
Where possible, this is my preferred method as it does a much more
complete job of fluid exchange in a much shorter time.