No. Gionee X1s does not have the hybrid sim slot. It has 2 dedicated sim card slots and 1 dedicated MicroSD card slot. You can use MicroSD card of up to 256GB with this phone.
Gionee X1s has 4000 mAh Li-Polymer battery. It offers 34 hours of talk time and standby time of 190 hours.
Gionee X1s has Android 7.0 Nougat and on top of it, Gionee has used Amigo 4.0 as the user interface.
Yes, Gionee X1s does have the VoLTE support.