via: Topbar - Tools - Panelize
At present, EasyEDA only support to panelize PCB self, in order to decrease the file size, the panelized file only panelize the board outline.
The Border height can not less then 5mm.
If you need to v-cut the panelized PCB, you can draw a track on the mechanical layer to indicate as below image:
then generate the Gerber.
JLCPCB will take care of your design, they know how to do.
Normally, all the PCB factory will support this panelized file, if you not sure, you need to contact your PCB factory support.