Être canon
This is a slang adjective used to describe a handsome or very seductive person. We can refer to this expressions with the weapons ''canons'' or the esthetical rules that were used a lot before in paintings, sculptures and arts in general - ''canons de beauté''
Être une bombe
We also say of a very attractive and sexy woman: « c'est une bombe » To be a knockout, to be a bomb