it is what it is vs so be it

it is what it is

phrase
  • A phrase expressing resignment to a situation or set of circumstances, usually without complaint; Thus meaning: this circumstance is simply a fact and must be accepted or dealt with as it exists. 

  • This thing has its own distinct nature; this thing is itself. 

so be it

phrase
  • An indication of acceptance, especially of a situation which is not entirely favorable. 

How often have the words it is what it is and so be it occurred in a corpus of books? (source: Google Ngram Viewer )