Where is the Search Widget?

The “widget” is now a [design] block accessible while editing the theme’s page and post templates, under “Appearance,” “Editor,” then select pages, templates or patterns where you want to edit to insert the search block.

Essentially, there are no more “widgets;” they are now known as “blocks,” and are accessible from the Editor.

For example, all of your websites pages will be accessible for editing of the layout from the Administrator’s menu: “Appearance,” Editor,” “Design,” “Pages.”