The FCC diagram of the phone looks a lot similar to the Realme C15. The listing shows that the phone has a battery model BLP729 which suggests a 5,000mAh battery, as Realme 5i has the same battery model. Realme RMX3063 will run Realme UI 1.0 custom skin on the top. FCC listing also reveals some connectivity options which are Bluetooth 4.2, Wi-Fi, 4G LTE, and GPS.
In the past, Realme RMX3063 appeared on Russian’s, EEC Indonesia’s TKDN, and Sertifikasi certifications. This hints that Realme could soon announce the smartphone in the global market. Details are few very as of now, but we can expect more details to surface online as the device gets closer to the launch. Source

Realme RMX3063 spotted on FCC  reveals 5 000mAh battery and triple rear cameras - 24Realme RMX3063 spotted on FCC  reveals 5 000mAh battery and triple rear cameras - 43Realme RMX3063 spotted on FCC  reveals 5 000mAh battery and triple rear cameras - 26