Formal:
* Ainsi soit-il: This is the most literal translation and is often used in religious or formal contexts.
* Qu'il en soit ainsi: This phrase means "let it be so" and is slightly less formal than "Ainsi soit-il."
Informal:
* Que cela soit: This translates to "let it be so" and is a more casual way of saying "so be it."
* C'est comme ça: This phrase means "it's like that" and conveys a sense of resignation or acceptance.
* Tant pis: This means "too bad" and expresses a sense of disappointment or resignation.
Other possibilities:
* Soit: This simple word means "be it" and can be used as a short way to say "so be it."
* Bon: This means "good" and can be used as a way of agreeing to something.
The best choice will depend on the specific situation and the desired tone.