Yes, Realme X does have the Corning Gorilla Glass 5 protection.
Realme X has industrial-grade polycarbonate back panel.
No. None of the Realme models comes with earphone. Realme X standard box packaging includes Realme X mobile, USB Type C Cable, Power Adapter, SIM Ejector tool, Protective case, and a user guide.
No. Realme X does not have the memory card slot but you should not worry about it because it comes with 128GB internal storage option, which is pretty big from a regular usage perspective. Besides, the mobile also has OTG support.