Honestly, I just go to carno island and find a couple of exes. I tried a trap but it went around it and I kept trying and well.... it said naaaaaaaah. So I just spit a couple of days at it with a long neck rifle or whatever and it fell asleep lol. So just look for lvl 10 or around that and it's ez. :)

Honestly much easier than I thought. Just make a trap, mine was on a raft, I suggest stone as they can’t break that. Get a flyer, but if not, just make sure to pump your speed. Find a Rex, life it up the ramp into the trap and shoot it. Mine took around 30 tranq arrows for a lvl 3 but idrc it’s low. It’s out and the torpor drops at an alright pace but bring narcs anyway. Hope this helps :)

If you bring your high health Spino, hit the Rex once and it will just get distracted attacking your Spino instead of you. Just dismount and tranq it then when its running away just chase it as you tranq it then it shall get unconscious. My plan became successful. The rex i tamed was a.lvl 10.

How to tame Rex.First you grab four normal gateways and a large bear trap, set down three of the gateways like a square with the trap in the middle. Make the Rex follow you into the trap you’ve got a few seconds to run round behind the Rex and place the last gateway knock it out and for mobile, sleep in a sleeping bag as this will make the Rex go to 0 food get a soothing balm and put some meat in the inventory and BAM you have a Rex, for PC follow the steps as mobile except you will not have any soothing balm and the trick will also not work, BYE!

So I got one of these bad boys pretty early on using this method: scout out a beach or clearing with a Rex and lure away or kill any trikes, stegos, or other big dinos in the area, as I’ve lost Rexes who have attacked too many dinos and been killed (don’t kill everything in the area, as you’ll see in a second). Bring at least 60 tranq arrows (you’re going to need most of them) then lure the Rex into attacking another Dino it can defeat like a carbonymems or diplodocus. The Rex will be preoccupied with the Dino and won’t aground you so you can pepper it with tranq arrows without worry. Try to aim for the head as you get more torpor per headshot. Rinse and repeat until the big guy drops. Torpor drains really slowly so you can tame with regular raw meat and patience if you have plenty of biotoxin.