Apple - Always show full URL in Safari address bar

Yes, it is possible.

Open Safari Preferences window using the keyboard shortcut Command + , or by going to Menu bar → Safari → Preferences..., and go to the Advanced tab. Check Show full website address.

Once this setting is enabled, Safari will always show the complete address for the currently open webpage, even when the Smart Search Field is not in focus.

Try Preferences / Advanced / Smart Search Field [ ] Show full website address:

(screenshot from Safari 11.1.2)