Elon Musk welcomed third child with Shivon Zilis earlier this year: report
What is the name of Elon Musk's child with Grimes born in 2021?

Elon Musk and Grimes' child born in 2021 is named Exa Dark Sideræl Musk, also known as "Y." Grimes announced the name change in March 2022, stating that they refer to her as "Y." The unique name has significant meanings, with "Exa" referring to a supercomputing term and "Dark" representing "the unknown."
How did Elon Musk respond to Page Six's congratulations in 2022?

In response to Page Six's congratulations in 2022, Elon Musk said, "Bravo to big families." He expressed his desire to have "as many [kids] as I am able to spend time with and be a good father3." Musk reiterated this sentiment in a tweet, stating, "A collapsing birth rate is the biggest danger civilization faces, by far."
What concern about civilization did Musk express in his 2022 tweet?

In his 2022 tweet, Elon Musk expressed concern about the "collapsing birth rate," stating that it is the biggest danger civilization faces by far.