(This is a solo tip idk how it would go in PVE or PVP) not that hard of a tame actually, it basicaly only take a baby apex creature (rex, spino, yuty etc...) to allow you to mount it, my first Carcha was a lvl 25 and i was level 32, i tamed 2 really low level spinos, made them breed, mercilessly killed their offspring, dragged it to the Carcha, the beast sniff the corpse giving you time to take some distance off of it, and once it eat its meal you mount ! Then you kill everything in your path, took me only one run with some hit taken (91% effectiveness) but i managed to get this wonderfull beast, though now its kinda useless because i can't ride her...

But technically you can get a Carcha really soon in the game, rex are kinda easy to tame for the SACRIFICE !