They are easy first get slow level if you are start game. Preferably a lvl1 to a lvl 10. Then knock it out with a slingshot or tranqs. I run in circles and knock it out. After that let starve for 3-5 minutes then feed green kibble ,crops , or mejos. After that give either narco berries or narcotics. Then you got a trike.
You can go to the swamp and find a good Triceratops then get a tintaboa and lure it to the triceratops and try to get them both to fight then the triceratops will pass out and then feed the triceratops to tame it
It’s can be easy to tame trikes, but for me, the area where they all are they team up together, so you attack one, you attack up to 3 or more. One on its own can be quite easy to tame/kill, but whatch out for nearby backup from other trikes.