I recommend starting at about .75 first, restart and test. I think mine is set to about .75 or .70. Damage isn't over the top. Unless an alpha t-rex tries to be my friend when I am busy. ?
Adjust the Dino Damage Multiplier
If you are using the UI to change settings, go to Modify Server Config on the bottom right of the server dashboard page.
See screenshot attached.
If you are using a custom ini, this is the value you want to edit
Under [ServerSettings] in the GameUserSettings.ini config file:
DinoDamageMultiplier=
Value is between 0 and 1, so 0.75 is 75% of normal. Higher values increase damage. Lower values decrease it.
Whichever option you edit with, make sure you restart the server.
You may also want to check if you have the server set to Hardcore mode.