What song did Alexander sing in the x factor?

You're likely referring to Alexander Jean, who was a contestant on the 2020 season of The X Factor UK. He did not sing any original songs on the show, but his most notable performances were:

* "You Say" by Lauren Daigle: This was his audition song and helped him earn a spot on the show.

* "When You Believe" by Whitney Houston and Mariah Carey: This was his performance during the Judges' Houses round, where he was mentored by Robbie Williams.

Alexander Jean unfortunately did not make it to the live shows.