I was also looking for this option. In rdr1 you could cycle between target with a flick of right stick. It doesn't seem like it's in rdr2. This sucks because if I have 2 deers in front of me, one with 3 stars pelt and another with 1 star pelt, it will aime at whatever's closer to me instead of being able to swith quickly with the right stick. Same in Dead Eye mode, it takes me a lot of time to cycle between multiple enemies. I'll test the contols and see if this changes anything and see if that works. I really miss the old targeting system from rdr1. :(