come on to vs sex up

come on to

verb
  • To make a romantic or sexual advance to. 

  • To start to. 

sex up

verb
  • To make more sexually attractive. 

  • To enhance in terms of fashionable appeal. 

  • To sensationalize. 

  • To arouse somebody sexually 

  • To take part in sexual acts with. 

How often have the words come on to and sex up occurred in a corpus of books? (source: Google Ngram Viewer )