With Astra you get three Sidebar options; viz. the right sidebar, left sidebar and an option that disables the sidebar. You can manage Sidebars in two ways.
Quick Steps on How to Manage Sidebars on Your Website
Step 1: Find the Sidebar Options under the customizer [ Appearance > Customize > Sidebar ] to edit Sidebar Options globally.
Step 2: Or manage the Sidebar Options on particular Pages and Posts from the Meta Settings.
Manage Sidebar globally in the customizer
You can find settings under Appearance > Customize > Sidebar
You can set a sidebar for the entire site with the Default Layout option. You can set a sidebar for particular Pages, Blog Posts, Blog Post Archives as well.
When one of the sidebars (left/right) is set, you can adjust its width.
Note: When you activate the addons for integrated plugins like WooCommerce, LifetLMS etc. you can see related option to manage sidebars
Managing sidebar for particular pages or posts
Astra also allows you to manage sidebars for a particular page or post through the meta settings.