Persevero is a free Genesis child theme written by wpbeginner.com. The Genesis Framework is used bty wpbeginner.com and one of the most popular frameworks for WordPress. The Genesis Framework is actually a parent theme. You will need to also install a child theme for Genesis.
List of Free Child Themes
You could purchase the Genesis Framework without purchasing a child theme with the intention of using a free Genesis Child theme. Here is a website wpcanada.ca with a list of free child themes.