There should be three adjuster screws on the cylinder. One adjusts the swing speed (how fast it closes), one adjusts the latch speed (how fast in closes in the final few inches) and one adjusts the back stop (the limit to how wide it opens).
Likely you need to adjust the latch speed and slow it down. You might also need to adjust the swing speed.
This door slams with zero slowing down. Is there anything I can do to improve it short of taking it apart, like lubrication, tightening bolts, etc? ( sh.itjust.works )