GNU/Linux Ubuntu 18.04 Epson XP-630/XP-640 Printer Setup – Step by step Guide
The linked tutorial shows you step-by-step How to Install Epson Expression Premium XP-630/XP-640 Series Printer/Scanner on Ubuntu 18.04 Bionic LTS GNU/Linux desktop – Step by step Tutorial.
And to Install Epson XP-630/XP-640 Printer on Ubuntu Bionic you need to Setup the Proprietary Driver.
Especially relevant: after the Driver Installation to achieve the Printer Setup follow guidance to Add Printer!
Using the Epson Printer Utility Software, you can check Ink Levels, View Error and other Status…
Finally, the guide includes also detailed instructions on How to Get Started Epson Scanning.

GNU/Linux Ubuntu 18.04 Epson XP-630/XP-640 Printer Installation Guide