Architecture Hub - Blog Sidebar

You can use custom sidebars for blog posts and blog archive pages. 

Add Sidebars

Go to Liquid > Theme Options > Sidebar to enable sidebars globally. 

You can also find this option in Elementor Page Settings. If you set it from there, sidebar will be enabled only for the page you're editing.

Edit Sidebars

Go to  Appearance > Widgets and find the related sidebar. Now you can drag and drop any pre-built widget to create your own sidebar.