SharePoint Framework React Search Box client side web part
Why another Search Box?
At the current moment (04.17) the default modern Site Page Search Box cannot be configured at all.Redirect from modern Site Page to classic search results page
This fulfill the business need, I created simple SPFx search box client side web part to redirect from modern Site Page to classic search results page url where more precise search result scopes configuration can be made.
Position below the actions section on a modern site page
I have added another custom property so the web part can appear just below the actions pane for better user experience. This option is not recommended for production because uses page DOM manipulation and if the Office 365 team change this DOM elements on the page then it may break the webpart visibility.