To enable the classic old legacy Search Box in Explorer on Windows 10, you can tweak the Registry or use Mach2. Do it if you do not like current default behavior.

On File Explorer, the search feature can help you find files and folders, ... In the search box, type the search query using ...

You can set File Explorer to automatically type into the Search Box or Select an item in Windows 11/10, by changing the File Explorer Options.

If you see one of these names (Dropbox, Box, OneDrive, etc.) in the Data field of the (Default) item, proceed to the next step. If you do not see this, hit the F3 key to find the next instance of ...