Why is my male cousin talking about sexual things to me is this normal

So we’ve only knew each other for 5 months he’s my second cousin he’s told me about girls he’s shagged and who he wants to shag he’s also told me how big his dick is is this normal

where 16 18

He also sometimes asks me if I think he looks sexy and he constantly stares and smiles at me and wants to be around me why is he behaving like this