In PixARK, the max dinosaur level is tied to your Difficulty Offset. This defaults to 0 and dinosaurs max out at around 60-70.
/ShooterGame/Saved/Config/WindowsServer/GameUserSettings.ini file, tweak the following:
This should yield dinos maxing out at around 150. You can tweak the number further from there - 1.0 is the max.
If that line isn't present, it's safe to to add it. See the related article for more information on server settings.