Having a pack of Dilos is a good way to combat one early on: they can slow it down with their spit attack, they can be generally hard for it to consistently hit, and carnos focus more on dinos than humans so if you get ambushed chances are it might change focus to your dilos. It can be possible to kill a carno with just 2 dilos if they can take a hit and you provide cover fire with any ranged option.
A simple way to get these guys is to simply distract them with something delicious. Command something tanky (Ex. Carbonemys) to attack them, then set them to passive so they don’t kill the Carno. Then, you can pelt it with a slingshot or bow and tranq arrow until it goes down. They don’t have the biggest torpor stat, so raising it to max won’t take many tranq arrows (5 if it is extremely low level)
Get on a large rock and start shooting tranq arrows, at least have 50 arrows. When it starts to run from low torpor jump down and chase it, make sure there aren’t any bugs or raptors that want to eat it
Find one and stalk it from a good distance and wait for it to attack something with a good sized health pool such as a stego and while they're fighting pelt it with tranq arrows, it will probably kill the other dino then start to run away, keep up with it and keep hitting it until it's knocked out