If you know what you're doing this tame is super easy.

First off, no matter the level all creatures bodies you drag to it will always fill the same amount of trust based off their drag weight(Lvl 100 Carchar will get the same trust as a Lvl 300 when fed the same dino). As many people have said a baby Spino, Rex, or Yuty will instantly fill this trust gauge.

Now the riding part is the trickier one. Many sources will say that you get thrown off at 20% tame but this is not true!!! You get thrown off when the rage meter in the bottom left gets to 100. Taming is based off of the killed creatures HP which makes this surprisingly easy as if you tame a really pumped up Bronto, Diplo, or Rex with only levels in health you can near insta tame, but be careful. A Rex at 111k HP only did 92.7% tame on a 3x Taming server so you need either a really buffed creature or a sacrifices. The Rex only gave 42 Rage as well so go wild and enjoy your new Carchar!!!!

-Dude0fPlague