It is in fact very rare for a hero to self praise in public that some other hero praised his acting skills. But NTR does this while sharing some anecdotes from the shooting of RRR.
Jr NTR said that Ram Charan was surprised by his acting skills during the shoot of the film RRR. But he didn't say anything to the public about Ram Chaan's acting skills as a matter of poking back.
He simply said that Ram Charan is a good human being and feels very lucky to have a friend like him.
He might have literally said this to make it a point that he is superior to Ram Charan's acting or he would have said this only to pull the attention of the audience for the publicity sake.