To tame a rex at low level need 3 large bear traps place them in line. Agro the rex it will stuck in 1st bear trap then start shooting tranq arrows ....then it will stck in second continue shooting tranq arrows ..pow rex is uncounsious .... but its little risky.😁
If you use the bear trap strategy which is if you lead it into a Dino gateway that is shaped in a triangle and with a bear trap in the middle (Large Beartrap) and when it is stuck you must put a dinogate behind it to trap it and then knock out.
The Rex are very slow . Put a stone gates around him while he is stuck and use a bear trap then put the x3-x4 stone gates then tranq him out . Make sure you clear the area before setting the bear traps others creature can spring it and u would be left with using your self or a tanky dino for a distraction