Can I use data only on iPhone se

Are you asking if you can use the phone without activating a cellular plan? To a point, possibly. You should be able to browse the web, send and receive emails, download apps, stream music with just WiFi. What you won't be able to do without an active SIM is sign into iMessage and FaceTime. And, of course, without an active SIM, you can't send SMS messages. Many third-party messaging apps require a mobile number but there may be some that don't. I don't think FaceBook Messenger does, for example.