By default, the search input field is hidden, and there is a search button (search-button.html) at the sidenav panel, as shown in this site. The search input field will be displayed when a user either:
Clicks the search button at the sidenav panel.
Presses the keyboard shortcut Ctrl + K (Linux, Windows) or ⌘ + K (macOS).
You can aslo place search icon (search-icon.html) in the navbar or sidenav to only display the icon (which does not have search bar text around it).