ED's is a percentage measure of the connection time. If the magnet are supposed to work shorter (lower ED), you can increase voltage and get more power.
Lower voltage gives lower force. But be wary, during high power / voltage, the coil will heat up fast and if you are not careful, it will melt / burn up.
This solenoid has a connection time on 100% at 12VDC. If you want a little more force, you can increase to 24VDC, if you do this, be aware of that the solenoid only can work at 25% ED.
100% ED at 12V - 25% ED at 24V
Stated holding power applies in ideal conditions without safety factor.