「よいではないか」 literally is "Isn't it OK", and usually it means "That's OK" or "No problem".
In general, 「よいではないか」 is a pompous expression and used by high-ranked people, such as
kings, mainly in fiction. Usually real people use shorter expressions such as "いいでしょ", "いいよね", "ダメ?", "問題ある?".
KING VS SANJI CONFIRMED
![finally :finally: :finally:](https://i.imgur.com/RzJ7T9e.png)
![finally :finally: :finally:](https://i.imgur.com/RzJ7T9e.png)