How is “so be it” used?

In Aquaman (2018), one line is: “So be it.”

Which movie is “so be it” from?

The clip at the top of this page is from Aquaman (2018).

Idiom

used to show that you accept sth and will not try to change it or cannot change it

formal · Heard in 1,138 movies

used to show that you accept sth and will not try to change it or cannot change it
If he doesn't want to be involved, then so be it.

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

So be it.

Said in 8 films · #1