This is a premium feature available with Astra Pro Addon plugin. To use these Pro features, you need to have the Astra theme along with the Astra Pro Addon installed on your website.
Astra theme provides basic options to style the blog archive and single blog page. Refer to the document here. While Blog Pro addon available with Astra Pro adds premium features to these options.
This module adds more options in the customizer for the blog layouts. To activate the addon you can find the setting under Appearance > Astra Options > Blog Pro
After activating the addon you can find additional settings under Appearance > Customize > Blog. Refer following documents to see detailed settings offered by the addon –