On mobile, if you’re fighting the trike head on, shoot at the legs!! The head has damage reduction so less damage from ranged weapons. However the legs are really hard to hit so just use a melee if you have high health and armor.
If yo encounter a trike with a glowing effect around it’s horns, you may want to turn around. The glowing effect is the result of a large predator and powerful predator(spinos are a key example) being nearby, which can save you, your tames, and your stuff.