AAA titles vary widely in what they need from a computer. Some are very CPU intensive while others more GPU intensive. Usually, the bar to just 'run' these games is set very low. For example, RDR2 has a 'minimum' graphics spec of an R9 280. Now, would I ever want to run RDR2 on an R9 280? Nope. If it does run, it will play and look like crap.
If your other specs are good you can expect to at least 'run' some of the new AAA titles. You will most likely have to turn down a bunch of graphics settings and I wouldn't expect the gaming experience to be good. It will depend on the title though.
It really depends, I have a R9 390 and i can run most games fine, but im pretty sure the newest triple A titles wont run that great, I bought the new COD: Modern Warfare and I got to say that my GPU Is struggling, im on the lowest settings and it drops frames very frequently.
If you are hoping to game on newer triple A titles, I couldn't recommand the R9 380.